Which of the following statements are true? Passing/calling by reference makes a single variable available in the scope of the function being called by giving the called function the variable's memory address. Passing/calling by value creates a copy of a variable in the function being called as a parameter. Passing/calling by reference creates a copy of a variable in the function being called as a parameter. Passing/calling by value makes a single variable available in the scope of the function being called by giving the called function the variable's memory address