How do I know this?

That this is true is demonstrated by the function named getData, which changes the values stored in the elements in the original array.

If a copy of the array were to be passed to the function named getData, it would not be possible for the function to deposit user input values into the original array. 

Rather, those values would be deposited in the copy of the array, which would cease to exist when the function terminates.

(See the lesson entitled Functions for a discussion of the difference between passing parameters by value and passing parameters by reference.)