1) Pregnancy and STD
2) Im not sure but condoms?
3) abstinence
4) The pill blocks hormones that control your ovulation so you don't release an egg and a condom prevents sperm from entering into the womb
5) Abstinence is 100% affective from preventing pregnancy and STDs bc you aren't doing the things that can cause it transmit them.
6) A condom must be used along side of birth control to prevent stds