Fill in the blanks:
$(a)$ Pneumonia is an example of . . . . . . disease.
$(b)$ Many skin diseases are caused by . . . . . . .
$(c)$ Antibiotics commonly block biochemical pathways important for the growth of . . . . . . .
$(d)$ Living organisms carrying the infecting agents from one person to another are called . . . . . . .

(N/A) Pneumonia is an infectious or communicable disease because it spreads from an infected person to a healthy person.
$(b)$ Many skin diseases,such as ringworm,are caused by fungi.
$(c)$ Antibiotics are medicines that specifically target and block biochemical pathways essential for the growth and survival of bacteria.
$(d)$ Living organisms that carry infectious agents from an infected host to a healthy person are known as vectors (e.g.,mosquitoes).