Final answer:
The option not necessary for method overloading is (d) Methods must have the same return type. Overloaded methods must have the same name, different signatures, and be in the same class but can have different return types.
Step-by-step explanation:
The requirement that is not necessary for method overloading is (d) Methods must have the same return type. In object-oriented programming, particularly in Java, method overloading is a feature that allows a class to have more than one method with the same name, provided that their parameters (signatures) are different. This concept is known as polymorphism. To be considered different, overloaded methods must have a different number of parameters or parameters of different types or with a different sequence.
Option (a) is correct; methods must have the same name to be overloaded. Option (b) says methods must have different signatures, which is true for overloading. Option (c) is also true; methods must be in the same class for method overloading. However, the return type is not a factor in overloading; methods can overload another with a different return type, hence option (d) is incorrect.