Question: Create an associative array using `$array1` as the keys and `$array2` as the values:

1. `$array3 = array_merge($array1, $array2);`
2. `$array3 = array_union($array1, $array2);`
3. `$array3 = array_keys($array1, $array2);`
4. `$array3 = array_combine($array1, $array2);`

Answer: The correct answer of the above question is Option D:`$array3 = array_combine($array1, $array2);`