Answer:
Option C, anthrax bacteria
Explanation:
All options i.e amoeba, paramecium and aloe vera plant have eukaryotic cell which have well defined nucleus and layered organelles.
A prokaryotic cell lacks well defined nucleus and also do not have some essential cell organelles. Along with this the cell organelles and nucleus do not have envelope or outer layer.
Only bacteria and archae have prokaryotic cells.
Hence, option C is correct
When a scientific experiment is carried out in a controlled setting, all variables are kept the same except for the C. experimental. Experimental variables are the things you are studying in the experiment and it is the only variable you can change.
The answer is A) Drinking water.
Edit: Thank you for Brainliest!!