Q. ​Trimethylamine oxide is the excretory product in 
(a) Marine teleosts 
(c) Molluses 
(b) Freshwater fishes 
(d) Amphibians. 

Dear student.

The correct option is  (a) Marine teleosts.

Marine teleost converts ammonia into trimethylamine (oxidized form is trimethylamine oxide),  trimethylamine oxide helps them in minimising entry of salts and loss of water.

Regards.