The correct choice is (d) qsort()
The explanation: void qsort(void *base, size_t nmemb, size_t size, int (*compar)(const void *, const void*))
The qsort() function is used to sort an array of nmemb objects, the initial element of array is pointed to by base. The size of each object in array is specified by size. The contents of the array are sorted into ascending order according to a comparison function pointed to by compar.