What should you use to return the number of non-null requests in an array?

The function that accurately returns the number of non-null requests in an array is countNonNull(). This function specifically counts the elements in an array that are not null, making it the most appropriate choice for this task.

While arrayCount() provides the total number of elements in an array, it does not specifically filter out null values. Similarly, length() simply returns the total number of items in the array, regardless of whether they are null or not. On the other hand, arraySum() is used to calculate the sum of all numeric values in the array, which is irrelevant when the goal is to count non-null elements.

Thus, countNonNull() stands out as the correct option since it precisely provides the count of non-null entries, addressing the requirement posed by the question effectively.