Correct Option: B. Faithfulness to partner Explanation of Why the Answer is Correct:

1. Understanding HIV Transmission: HIV (Human Immunodeficiency Virus) is primarily transmitted through unprotected sexual contact, sharing of needles, and from mother to child during childbirth or breastfeeding. The most common mode of transmission is through sexual intercourse.
2. Role of Faithfulness: Being faithful to one partner significantly reduces the risk of HIV transmission. If both partners are monogamous and one is HIV-negative, the risk of transmission is minimized. This is because the virus cannot be transmitted if neither partner is infected.
3. Behavioral Prevention: Faithfulness is a behavioral strategy that encourages individuals to engage in sexual relationships with only one partner. This reduces the number of potential exposures to the virus, as each additional partner increases the risk of encountering someone who may be HIV-positive.
4. Complementary Strategies: While faithfulness is a strong preventive measure, it is often recommended to be combined with other strategies such as using condoms, regular testing, and knowing your partner's HIV status. However, the question specifically asks for one preventive measure, making faithfulness the most direct and effective answer.

Explanation of Why the Other Options are Wrong or Weaker:

• A. A member of the Red Cross Society:
• While being a member of the Red Cross Society may involve activities related to health education and community service, it does not directly prevent HIV infection. Membership alone does not influence personal behavior or reduce the risk of transmission.
• C. Becoming a medical staff:
• While medical staff can play a crucial role in HIV prevention through education, testing, and treatment, simply being a medical staff member does not inherently prevent HIV infection for the individual. It is the actions taken by medical professionals that can help prevent the spread of HIV, not the title itself.
• D. Membership of campaigns against AIDS:
• Joining campaigns against AIDS can raise awareness and promote education about HIV prevention, but it does not directly prevent an individual from contracting the virus. Active participation in such campaigns can be beneficial, but it does not replace the need for personal preventive measures like faithfulness.

Summary of Key Points:

• Faithfulness to a partner significantly reduces the risk of HIV transmission by limiting exposure to the virus.
• HIV is primarily transmitted through unprotected sexual contact, making monogamous relationships a strong preventive measure.
• Other options, while potentially beneficial in a broader context, do not directly prevent HIV infection.
• Combining faithfulness with other preventive strategies (like condom use and regular testing) enhances overall protection against HIV.

This thorough understanding of the preventive measures against HIV/AIDS will help you in your studies and future discussions on public health and personal responsibility.