please explain

1. What is the asymptotic run-time (Big-"Oh") of the following snippet of code? Input A: array, n: size of array for x in A do output x sum no c * g(n) a.s 4. What is the benefit of using a "dummy" head and tail pointer in a linked list implementation? a. So your list will never be full b. So your list will never be empty c. To treat all insert operations equally d. To return an error when pushing onto a full list or off an empty list