Which shows a recursive and an explicit formula for a sequence whose initial term is 14 and whose common difference is −4? a. a(1) = 14; a(n) = (n − 1) −4; a(n) = 14 + (n − 1)(−4) b. a(1) = 14; a(n) = (n + 1) −4; a(n) = 14 + (n − 1)(−4) c. a(1) = 14; a(n) = (n − 1) − 14; a(n) = 14 + (n − 1)(−14) d. a(1) = 14; a(n) = (n + 1) − 14; a(n) = 14 + (n + 1)(14)