It's important to use condoms to help reduce the spread of STI (sexually transmitted infections). These infections include HIV (Human Immunodeficiency Virus), chlamydia, genital herpes, genital warts, gonorrhea, hepatitis B, and syphilis.
She should try to get a day off so she can let her muscles relax and have time to rebuild new muscle. Remember that muscle grows slowly so within 24 hours muscle starts to grow thus she should rest for at least 1 or 2 days so she doesn't exhaust her body.
I think their probably stressed out about life.
It would be D. because nothing can be 100% you can still get pregnant from all of those things.
hope i helped! :) <span />