Question

Foul smell in the water of tanks, ponds etc. is due to [MP PMT 1994]
A) Anaerobiosis
B) Aerobiosis
C) Biological magnification
D) Psammophytes

Answer 1

I think the option  A) Anaerobiosis.

    Foul smell in the water of tanks , ponds etc is due to Anaerobiosis.

   The lack of fresh air and Oxygen inside water tanks and ponds results in anaerobic processes there.  The products (alcohols/lactic acids/gases) of anaerobiotic fermentation cause the foul smell. The smell is foul and unbearable for human beings as there is not enough Oxygen and there are other gases which strongly affect our smell sensors.

Answer 2

foul smell in the water of tanks, ponds etc. is due to A) anaerobiosis. anaerobiosis means respiration in the absence of oxygen.