Answer;
The best contraceptive method for sexually active people not in a monogamous relationship is Condoms.
Explanation;
Contraception and fertility control are methods or devices that are used to prevent pregnancy. Contraception methods ,may be classified as; hormonal methods (such as combined hormones), barrier methods (e.g use of condoms), Intrauterine Device use, and Natural methods (such as abstinence). Condoms is a type of barrier methods of contraception that is best for sexually active people that are not in a monogamous relationship.