The correct option is (c) natcasesort()
The explanation is: The function natcasesort() in PHP sorts an array by using a “natural order” algorithm. All the values keep their original keys. Eg: In a natural algorithm, as the number 2 is less than the number 10. But in computer sorting, 10 is less than 2, because the first number in “10” is less than 2. The function is case-insensitive.