The following is a list that describes micro-organisms.

They:
i Play a significant role as decomposers
ii Are the major pathogens of humans
iii Are obligate parasites
iv Reproduce within host cells
Which of the following are of biological importance in viruses?
A i, ii and iii
B ii, iii and iv
C i, iii and iv
D ii and iv only

The correct answer is D) ii and iv only.