What are the explicit equation and domain for a geometric sequence with a first term of 4 and a second term of −12? a. an = 4(−3)n − 1; all integers where n ≥ 1 b. an = 4(−3)n − 1; all integers where n ≥ 0 c. an = 4(36)n − 1; all integers where n ≥ 1 d. an = 4(36)n − 1; all integers where n ≥ 0