Questions: Multiple Choice Question Depo-Provera, the first injectable contraceptive approved for use in the United States, prevents pregnancy by: causing permanent infertility providing a combination of hormones preventing ovulation preventing sperm from entering the vagina

The answer is the third one: preventing ovulation.

Explanation for each option:

1. Causing permanent infertility: This is incorrect. Depo-Provera does not cause permanent infertility. It is a reversible form of contraception, and fertility typically returns after discontinuation, although it may take some time.

2. Providing a combination of hormones: This is incorrect. Depo-Provera contains only one hormone, which is a synthetic form of progesterone called medroxyprogesterone acetate. It does not provide a combination of hormones.

3. Preventing ovulation: This is correct. Depo-Provera works primarily by preventing ovulation, which means it stops the ovaries from releasing an egg. Without ovulation, there is no egg available for fertilization, thus preventing pregnancy.

4. Preventing sperm from entering the vagina: This is incorrect. Depo-Provera does not act as a barrier method. It does not prevent sperm from entering the vagina; instead, it works hormonally to prevent ovulation and also thickens cervical mucus to make it more difficult for sperm to reach any egg that might be released.

Summary: Depo-Provera prevents pregnancy primarily by preventing ovulation.