Segmentation fault with no compile error. I've researched alot with no answers

Question

I am working on this program that takes in a file and stores the information then will break it down and print based off what the user wants. but when I compile I receive no error. but when I execute I receive a Segmentation fault (core dumped) I've really looked into my code but I do not think I understand enough about C to understand the problem. Please let me know what you think.

   #include <stdio.h>
   #include <string.h>
   #include <stdlib.h>
   #define SIZE 15
   #define Line_size 100
  
   typedef struct {
       //parts of the struct
       int course_number;
      char course_name[Line_size];
      int seat_number;
      char day[Line_size];
      char teacher[Line_size];
     char time[Line_size];
 } course_t;
 
  //declare other functions
  void store(course_t courses[]);
  void seperate(course_t courses[]);
  void print(course_t courses);
 
  int main(void){
 
      course_t courses[SIZE];
      store(courses);
      seperate(courses);
 
      return(0);
  }
  void store(course_t courses[]){
 
      FILE *file = fopen("classes.csv", "r");
 
      //buf holds each line
      char buf[Line_size];
 
      //loop over every line and store info
      for (int i = 0; i <SIZE; i++){
          fgets(buf, Line_size, file);
          //printf("%s", buf);
 
          //get the class num
          strtok(buf, " ");
          char *class_num = strtok(NULL, ",");
          courses[i].course_number = atoi(class_num);
 
          //get class name
          char *class_name = strtok(NULL, ",");
          strcpy(courses[i].course_name, class_name);
 
          char *s_num = strtok(NULL, ",");
          s_num = strtok(NULL, ",");
          courses[i].seat_number = atoi(s_num);
 
          char *teach = strtok(NULL, "'");
              teach = strtok(NULL, "'");
              teach = strtok(NULL, "'");
          strcpy(courses[i].teacher, teach);
 
          char *d = strtok(NULL, " ");
          strcpy(courses[i].day, d);
 
          char *tim = strtok(NULL, " ");
          strcpy(courses[i].time, tim);
 
      }
      fclose(file);
  }
 
 
  void seperate(course_t courses[]){
 
     int choice;
 
      //printf("working so far?");
          do{
    //prints list of options to choose from
      printf("Choices:\n1 - Print all available classes\n2 - print class given course id\n3 - print all classes given day of week co
    mbo\n4 - print all classes under certain # of seats\n5 - prints all classes you would be interested in taking if you want a CS deg
    ree\n6 -quit\n");
      //the process of printing all of the statements starts here
      //they will be sorted by an if else statement and then the results will print and scan depending on the users choice
 
          scanf("%d", &choice);
          if (choice == 6){
              printf("You exited the program\n");
          }
          else if (choice == 1){
                  //to find the number of chairs in a class
          }
          else if (choice == 2){
              char *temp = NULL;
 

              printf("Enter class id:");
              scanf("%s", temp);
 
          }
 
 
 
         else if (choice == 3){
             char *dow = NULL;
             //printf("%s", day1);
             printf("Enter a day of week combination ");
             scanf("%s", dow);
         }

         else if (choice ==4){
             int seat = 0;
             printf("Enter maximum number of seat: ");
            scanf("%d", &seat);

            for(int i = 0; i < SIZE; i++){
                 if (courses[i].seat_number >= seat){
                     print(courses[i]);
                 }else{
                     printf("num");
                 }
             }
         }
         else if (choice ==5){
                  //to find the number of chairs in a class
     }


     } while (choice != 6);
 }



 void print(course_t course){


     printf("%-35d %-12s %d\n%-5s %-5s %-5s\n", course.course_number, course.course_name, course.seat_number, course.teacher, cours
    e.day, course.time);



 }
                                                                  

EDIT

upon request here is the input data.

 CSCI 107,Joy and Beauty of Computing,33930,62,0,62,Paxton John T,MWF 1000-1050
   CSCI 112,Programming with C I,31368,175,0,175,Cummings Mary A,MWF 0900-0950
   CSCI 127,Joy and Beauty of Data,33832,155,0,155,DeFrance Daniel Louis,MWF 0900-0950
   CSCI 132,Bsc Data Structures/Algorithms,30271,156,0,156,DeFrance Daniel Louis,MWF 1510-1600
   CSCI 215,Social & Ethical Issues in CS,33931,60,0,60,Cummings Mary A,TR 1505-1555
   CSCI 232,Data Structures and Algorithms,31508,128,0,128,Lloyd Hunter S,TR 1050-1205
   CSCI 246,Discrete Structures,33580,84,0,84,Zhu Binhai,MWF 0800-0850
   CSCI 305,Concepts/Programming Languages,30279,144,0,144,Lloyd Hunter S,MWF 0800-0850
   CSCI 338,Computer Science Theory,30278,140,0,140,Zhu Binhai,MWF 1100-1150
  CSCI 347,Data Mining,34852,75,0,75,Neeley Veronika,MWF 1310-1400
  CSCI 366,Computer Systems,34889,60,0,60,Wittie Mike,MWF 0900-0950
  CSCI 441,Computer Graphics,35118,65,0,65,Millman David,TR 1630-1745
  CSCI 446,Artificial Intelligence,35119,63,0,63,Sheppard John W,TR 0925-1040
  CSCI 455,Embedded Systems: Robotics,35117,84,0,84,Lloyd Hunter S,MWF 1200-1250
  CSCI 468,Compilers,31511,80,0,80,Kahanda Indika M,MWF 1510-1600