C# question from MVA videos

It is not a good question. Let us see why.

1. Term function is not used in C#. It is replaced by term method. So that rules out last option.
2. Property is a way to encapsulate your private members. It helps hiding the class internals that are associated with the variable. It definitely is something that helps managing private members.
3. Method can of course be used to manipulate variables as well. But IMHO that is not really what their only purpose should be. I mean something like this would not really make much sense:

public void SetSomeVariable(string valueToChange){
somePrivateString = valueToChange;
}

Hence, I would rule that out as well.
4. Object of a class is what is needed to access any non-static member of the class. It is a prerequisite if we are dealing with non static (instance) members.

Looking at above, I would say properties with objects are used to manage instance based private members.