How do you check if a variable is an array in PHP?

The is_array() function is the correct approach to check whether a variable is an array in PHP. This built-in function takes one parameter and returns true if the variable being evaluated is an array, and false otherwise. Its purpose is specifically to validate the type of a variable, making it a straightforward and reliable method for checking array structures.

The other options provided do not correspond to any functions defined in the PHP standard library. check_array(), is_array_variable(), and var_is_array() do not exist in PHP and would lead to errors if called. Thus, relying on is_array() is not only the correct method but also the best practice for examining variable types in PHP.