in c++ object oriented programming :

In order for a non-member function to have access to the private members of a class, the class must declare that function a: (a) inline (b) friend (c) static (d) None of the above Which of the following is an accurate comparison between const call-by-value and call-by- reference? (a) Both protect against changing the caller's argument (b) const call-by-value copies the argument whereas call-by-reference does not (c) const call-by-value uses less memory than call-by-reference in making the copy (d) None of the above