HIV/AIDS could be prevented by:Cooking meat thoroughly before eatingFungicide sprayAvoiding unprotected sex Vaccination

HIV/AIDS prevention strategies primarily focus on reducing the risk of transmission of the virus. Among the options provided, only one is directly related to HIV/AIDS prevention.

1. Cooking meat thoroughly before eating: This measure is important for preventing foodborne illnesses but does not prevent the transmission of HIV/AIDS. HIV is not transmitted through food.

2. Fungicide spray: This option is irrelevant to HIV/AIDS prevention as it deals with treating fungal infections, not viral infections like HIV.

3. Avoiding unprotected sex: This is a critical preventive measure against HIV transmission. Engaging in protected sex by using condoms significantly reduces the risk of transmitting HIV and other sexually transmitted infections (STIs).

4. Vaccination: As of now, there is no effective vaccine for HIV/AIDS that can completely prevent infection, although research is ongoing in this area.

Conclusion

From the options listed, avoiding unprotected sex is the most effective method for preventing HIV/AIDS transmission. It is essential to use condoms and engage in safe sexual practices to significantly reduce the risk of infection.