Which of the following statements is true? a. A friend function can declare itself to be a friend of a class. b. A friend function can declare itself to be a friend of another function. c. Both of the...

Which of the following statements is true?

a. A friend function can declare itself to be a friend of a class.

b. A friend function can declare itself to be a friend of another function.

c. Both of the above are true.

d. None of the above is true.