Question

Which group of microorganisms contain only pathogenic members ?

Answer 1

Here is your answer...

There are basically and mainly four major groups of micro-organisms -
1) Bacteria
2) Algae
3) Protozoans
4) Fungi

And one more which is neither living or non-living- Viruses

But nowadays they are being considered as living so,
If you are someone of view that viruses are living, your answer is viruses
If you are someone of view that viruses are non-living, your answer is protozoans.

NOT EVERY MEMBER OF THESE ARE BAD, BUT MOST OF THEM ARE....

Answer 2

virus is the correct answer because every virus causes only disease no useful things.