Final answer:
option a and c.The operations that can be performed on array variables include Assignment and Parameter passing by reference, allowing changes to individual elements and the ability to modify the array within functions, respectively.
Step-by-step explanation:
Among the aggregate operations that can be executed on array variables, the correct options are Assignment (B) and Parameter passing by reference (D). The Assignment operation allows you to set or change the value of an element in an array. For instance, assigning a value to an array index like array[0] = 5. Parameter passing by reference implies that when an array is passed to a function, the reference to the original array is used, allowing the function to modify the original array's contents.
Option A, Arithmetic, is not applicable to array variables as a whole; arithmetic operations are performed on individual elements of an array rather than the array as an entire object. Option C, Function returning a value, isn't an operation performed on an array itself, though functions can certainly return arrays as values.