What does mercury act as when it enters the human body? 

A)  as a neurotoxin 
B)  as a mutagen 
C)  as an allergen 
D)  as a carcinogen

Neurotoxin

A type of toxin that specifically targets neural tissues, potentially causing damage to the nervous system.

Mutagen

An agent, such as radiation or a chemical substance, that causes genetic mutation.

Carcinogen

is any substance, radionuclide, or radiation that promotes carcinogenesis, the formation of cancer, by altering cellular metabolism or damaging DNA directly in cells.