Nylon-66 is a polyamide obtained by the reaction of
(a) COOH(CH2)4COOH + H2NC6H4NH2 - (p)
(b) COOH(CH2)4COOH + NH2(CH2)6NH2
(c) COOH(CH2)4COOH + NH2(CH2)4NH2
(d) COOHC6H4COOH - (p) + NH2(CH2)6NH2