Ternary operator why c++ gives rvalue but lvalue in c

Question

int a,b;
...
((a>b) ? a : b) = value ;

This is error in c.

lvalue required for assigning value.

But This works fine in c++.

Why not in c and in c++? whats the difference? whats happening? i know that it returns lvalue in c thats why error. fine. But why it is so in c and c++ allowed it by returning rvalue?