Which statement is true?

a$)$ When an argument is passed call by reference, a copy of the argument's value is made and passed to the called function.

b$)$ Call by value should be used whenever the called function does not need to modify the value of the caller's orlginal value.

With call by reference, changes to the passed value do not affect the orighal variable's value in the calling functions.

d$)$ Call by value should only be used with trusted called functions that need to modify the original variable.