how did we get these answers?

Question 1: O O . 1) After solving the following recurrence functions, state their complexity category a) T(n) = 2T(n/2) + 1 O(n) (Ign) (nlgn) (n) None of the above b) T(n) = Tn/2) + n (n) (Ign) (nlgn) (n) None of the above O O