**Explanation:**

**a) Chlamydiasis, gonorrhoea, trichomoniasis:**
- Chlamydia, gonorrhea, and trichomoniasis are all sexually transmitted infections (STIs) that can be cured with appropriate treatment.
- Chlamydia and gonorrhea are bacterial infections and can be treated with antibiotics.
- Trichomoniasis is caused by a parasite and can be treated with a specific medication.

**b) Chancroid, syphilis, genital warts:**
- Chancroid is a bacterial infection that causes painful sores in the genital area. It can be cured with antibiotics.
- Syphilis is a bacterial infection that can be cured with antibiotics, especially in the early stages. If left untreated, it can lead to serious complications.
- Genital warts are caused by the human papillomavirus (HPV) and cannot be cured completely. However, the warts can be removed or treated, and the virus can be managed to reduce the risk of transmission and complications.

**c) AIDS, syphilis, hepatitis B:**
- AIDS (Acquired Immunodeficiency Syndrome) is caused by the Human Immunodeficiency Virus (HIV) and currently has no cure. However, with antiretroviral therapy (ART), the progression of HIV can be controlled, and individuals can live long and healthy lives.
- Syphilis, as mentioned earlier, is a bacterial infection and can be cured with antibiotics.
- Hepatitis B is a viral infection that can cause liver damage and other complications. While there is no cure for hepatitis B, antiviral medications can help manage the infection and reduce the risk of complications.

**d) AIDS, genital herpes, hepatitis B:**
- As explained earlier, AIDS (caused by HIV) and hepatitis B do not have a complete cure. However, their progression can be managed with appropriate medications.
- Genital herpes is caused by the herpes simplex virus (HSV) and cannot be cured completely. The virus remains in the body and can cause recurring outbreaks. However, antiviral medications can help manage the symptoms and reduce the frequency and severity of outbreaks.

In summary, the STDs that are not completely curable are AIDS, genital herpes, and hepatitis B (option D). Proper management and treatment can control these infections and improve the quality of life for affected individuals.