Abstinence is the only way that people can be completely certain that they are not at risk for STIs and/or unintended pregnancy.
a) Abstinence is the only way that people can be completely certain that they are not at risk for STIs and/or unintended pregnancy.

b) Regular testing for STIs guarantees complete prevention against their transmission.

c) Using contraception methods ensures absolute protection against both STIs and unintended pregnancy.

d) Monogamous relationships eliminate the risk of STIs and unintended pregnancy entirely.