Which recursive formula can be used to generate the sequence below, where f(1) = 6 and n ≥ 1?

6, 1, –4, –9, –14, …

a.)f (n + 1) = f(n) + 5
b.)f (n + 1) = f(n) – 5
c.)f (n) = f(n + 1 ) – 5
d.)f (n + 1) = –5f(n)