Explain the meaning of the ampersand in the following PHP code: `function customSort(array & $array){}`

Question

```php
<?php
function customSort(array & $array){
}
```
What does the"&"mean?

Accepted Answer

It allows you to modify the variable directly from the function.

Answer

It avoids the modification of the variable from the function.

Answer

It allows you to reserve a specific memory space for the variable.

Answer

It is used to indicate that the global variable must be used if no variable is provided.

Question from the PHP7 test