C Programming - Functions

A function cannot be defined inside the another function, but a function can be called inside a another function.

True, A function cannot return more than one value at a time. because after returning a value the control is given back to calling function.

True, The default return type for a function is int.

True, A function can be called either call by value or call by reference.

Example:

Call by value means c = sub(a, b); here value of a and b are passed.

Call by reference means c = sub(&a, &b); here address of a and b are passed.