Write the next sentence in the following story.

How to protect against an std
Consider abstinence.
The most surefire way of preventing an std is to not engage in sexual behaviors. These behaviors include oral sex, vaginal sex, and anal sex.

Pick from:
a). Engaging in sexual activities for long periods of time, though possible, may not lead to regular abstinence. Abstinence may have helped to prevent an std, but not necessarily lessens your risk of having an std.
b). Abstinence is not a choice for your partner. Abstinence just makes the condition worse.
c). Abstinence is a good choice for some people but is not realistic or desirable for many people, however. If abstinence is not an option, there are many ways to reduce your risk of infection.
d). If you are about to engage in sexual activity, refrain from having intercourse if you are at risk of developing an std. Stds, and vaginal sex, can be sexually transmitted.. The answer should be
c).