A function cannot be overloaded by only by its return type

Which of the followng cannot be taken as a feature of open type circulatory system ?

Which one of the following function contains only one integer in its range ? [ Note sgn (k) denotes the signum function of k.]

One of the following functions of the cell membrane cannot be attributed to its fluid occurs

What is the usual name of the forces which cannot produce motion in a body but only change its shape ?

Types of functions and Inverse of a Function