The overall number of cases of STIs is:

Choice A reason: Human immunodeficiency virus (HIV) is incorrect because it is not characterized by recurrent episodes. It is a chronic infection that progressively damages the immune system and can lead to acquired immunodeficiency syndrome (AIDS).

Choice B reason: Herpes simplex virus (HSV) 2 is correct because it is characterized by recurrent episodes. It is a viral infection that causes genital herpes, which is marked by painful blisters and sores in the genital area. The virus remains dormant in the nerve cells and can reactivate periodically, causing outbreaks.

Choice C reason: Human papillomavirus (HPV) is incorrect because it is not characterized by recurrent episodes. It is a viral infection that causes genital warts and cervical cancer. The virus can persist in the body for a long time, but it does not cause repeated symptoms.

Choice D reason: Cytomegalovirus (CMV) is incorrect because it is not characterized by recurrent episodes. It is a viral infection that usually causes mild or no symptoms in healthy people, but can be serious in people with weakened immune systems or unborn babies. The virus can remain latent in the body, but it does not cause flare-ups.

Choice A reason: Using male condoms is one of the most effective ways to prevent the transmission of STDs, especially those caused by viruses or bacteria. However, condoms are not 100% foolproof and may not protect against some STDs that can be spread by skin-to-skin contact, such as herpes or HPV.

Choice B reason: Having multiple sex partners increases the risk of getting an STD, as it exposes the person to more potential sources of infection. The more partners a person has, the more likely they are to encounter someone who has an STD or does not know their status.

Choice C reason: Delaying sexual relations as long as possible is another way to lower the risk of getting an STD, as it reduces the number of sexual exposures and the chances of encountering an infected partner. Young people are especially vulnerable to STDs, as they may have less knowledge, experience, or access to preventive measures.

Choice D reason: All of the above choices are valid ways to lower the risk of getting an STD, but none of them are sufficient on their own. The best way to prevent STDs is to practice abstinence or be in a mutually monogamous relationship with a tested and uninfected partner. Additionally, regular testing, screening, and treatment are essential for detecting and curing STDs before they cause serious complications.