The first four terms of a sequence are shown below: 7, 4, 1, -2 which of the following functions best defines this sequence? a. f(1) = 7, f(n + 1) = f(n) + 3; for n ≥ 1 b. f(1) = 7, f(n + 1) = f(n) - 3; for n ≥ 1 c. f(1) = 7, f(n + 1) = f(n) - 4; for n ≥ 1 d. f(1) = 7, f(n + 1) = f(n) + 4; for n ≥ 1