A, B and C are three common STDs. A and C are caused by bacteria whereas B is caused by a virus D. The virus D reduces the immunity of the infected person to such a low level that the person can die of even very mild diseases.

(a) What could A and C be?

(b) What is B?

(c) Name the virus D ?

(d) How can A, B and C be caused ?

(e) Out of A, B and C, which one does not have a definite cure as yet ?