Final answer:
In Java, when an array is passed to a method, a reference to the array is passed, not a copy of the array itself. Thus, the correct answer is a reference to the array object rats.
Step-by-step explanation:
When a method is called in Java and an array is passed as an argument, Java uses what is known as call by value. However, in the case of an array or any object, the value that is passed by value is actually a reference to the object, not the object itself.
In the given scenario, where a routine is called with an array rats (routine rats), what is being passed to the method is not a copy of the array itself, but a reference to the array object rats. This means that while the routine has its own reference to work with, it points to the same array that the caller sees, allowing changes made within the method to affect the original array.
The correct answer is C. A reference to the array object rats.