Final answer:
Individual elements of an array can be passed to a user-defined function either by value or by reference, depending on the choice of the programmer and the programming language used.
Step-by-step explanation:
Individual elements of an array can be passed by either value or reference to a user-defined function depending on the programming language and the specific syntax used in the function call and definition. Typically, in languages like C and C++, you can choose to pass an element by value, which creates a copy of that element for use within the function, or by reference, which allows the function to directly modify the original element in the array.