The correct answer is A. Toxicology.
Toxicology is the study of the adverse effects of chemicals on living organisms. It is a multidisciplinary science that encompasses the study of the mechanisms of action of toxicants, the diagnosis and treatment of poisoning, and the prevention of exposure to toxicants.
Microbiology is the study of microorganisms, which are organisms that are too small to be seen with the naked eye. Microorganisms include bacteria, viruses, fungi, and protozoa. Microbiology is a broad field that encompasses the study of the structure, function, and metabolism of microorganisms, as well as their interactions with other organisms and the environment.
Limnology is the study of inland waters, such as lakes, rivers, and ponds. Limnologists study the physical, chemical, and biological characteristics of these waters, as well as the interactions between these characteristics and the organisms that live in them.
None of these options is a correct answer.