3. What is the worst-case runtime complexity of locating and returning the last element in an unsorted array-backed list of N elements? (b) O(log N) (c) O(N) (d) O(Nlog N) 4. What is the worst-case runtime complexity of determining whether a given value exists in an unsorted array-backed list of N elements? (b) O(log N) (c) O(N) (d) O(N log N) 5. What is the worst-case runtime complexity of deleting a random element from an array-backed list of N elements? (b) O(log N) (c) O(N) (d) O(Nlog N)