Choice A rationale:

Using condoms consistently and correctly is a valid statement. Condoms provide a barrier that can significantly reduce the risk of STI transmission by preventing direct genital contact.

Choice B rationale:

Getting regular STI testing is crucial for early detection and treatment, even if no symptoms are present. Many STIs can remain asymptomatic, and delaying testing could lead to complications and further spread.

Choice C rationale:

Avoiding sexual contact with multiple partners can indeed lower the risk of STIs, as it reduces exposure to potential carriers. However, this choice does not require further education.

Choice D rationale:

Practicing abstinence is an effective method to prevent STIs, but it may not be feasible for everyone. It is not the "most effective" method, as condoms and regular testing are also vital strategies.