Explanation:
HIV: HIV means human immuno-deficiency virus. It is a type of virus that attacks, weakens, and destroys the white blood cells which are responsible for immunity in the human body.
AIDS: AIDS means acquired immune deficiency syndrome. It refers to a condition in which an HIV-positive person becomes immune deficient as a result of the destruction of the immune system which makes the victims becomes vulnerable to different forms of infections to the human body.

b.

Symptoms of AIDS
Frequent diarrhoea.
Tuberculosis.
Pneumonia.
Persistent fever.
Weight loss.
Recurrent skin infection.
Excessive sweating.
Recurrent fungal infection in the mouth and throat.
Aching muscles and joints.
Hepatitis b.
Memory loss.
Anaemia.
Blurred/distorted vision.
Swollen lymph glands
Nausea.
Mouth, genital and anal sores
Chronic fatigue
Chills.