Option D is correct both hepatitis B and AIDS are caused by the infected blood or body fluids.. hepatitis B virus is present in saliva.. but AIDS does not caused through the saliva.. AIDS virese does not present in the saliva..

Hepatitis B and AIDS are both caused by retroviruses and transmitted through infected blood. Let's understand each of these points in detail:

Caused by Retroviruses:
- Hepatitis B is caused by the Hepatitis B virus (HBV), which is a member of the Hepadnaviridae family. It is a DNA virus that replicates through an RNA intermediate using the reverse transcriptase enzyme, making it a retrovirus.
- AIDS (Acquired Immunodeficiency Syndrome) is caused by the Human Immunodeficiency Virus (HIV), which belongs to the Retroviridae family. HIV is also a retrovirus that contains RNA as its genetic material and uses reverse transcriptase to convert its RNA into DNA, which is then integrated into the host cell's genome.

Transmitted through infected blood:
- Both Hepatitis B and AIDS can be transmitted through infected blood, making blood transfusions, sharing needles, or other forms of direct blood contact potential routes of transmission.
- Hepatitis B can also be transmitted through other body fluids like saliva, semen, and vaginal fluids.
- AIDS can also be transmitted through other body fluids like semen, vaginal fluids, breast milk, and blood-contaminated instruments.

Other modes of transmission:
- Hepatitis B can also be transmitted through unprotected sex with an infected person, sharing needles or syringes, and from an infected mother to her baby during childbirth.
- AIDS can be transmitted through unprotected sex with an infected person, sharing needles or syringes, from an infected mother to her baby during childbirth or breastfeeding, and rarely through organ transplantation or occupational exposure (e.g., accidental needle sticks in healthcare settings).

Congenital diseases:
- Neither Hepatitis B nor AIDS are congenital diseases. Congenital diseases are conditions present at birth and are caused by genetic or developmental factors.

In conclusion, both Hepatitis B and AIDS are caused by retroviruses but are primarily transmitted through infected blood. It is important to practice safe blood transfusion procedures, use sterile needles, and take precautions during sexual activities to prevent the transmission of these diseases.