In PHP, what is the use of `array_push()`?

The function array_push() in PHP is specifically designed to add one or more elements to the end of an array. When you call array_push(), you provide the target array followed by the element(s) you wish to add. This operation modifies the original array by appending the new items to its end and returns the new total number of elements in the array.

For instance, if you have an array defined as $arr = [1, 2, 3]; and you use array_push($arr, 4, 5);, the array $arr will then contain [1, 2, 3, 4, 5]. This makes array_push() a vital function when you need to dynamically grow the size of your array while maintaining the order of elements.

In contrast, the other choices outline different functionalities that are not related to what array_push() does. Reversing an array, removing the last element, or sorting an array in ascending order are handled by different functions like array_reverse(), array_pop(), and sort() respectively.