This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Which of the following is an example of a direct acting toxin? 
Select and explain. 
A. Acetaminophen, B. Mercuric chloride, C. Carbon tetrachloride, D. Bromobenzene
B: Mercuric chloride
Answer: B: Mercuric chloride 
Explanation: Direct-acting toxins:
Some toxins act directly by combining with a critical molecular component or cellular organelle. For example, in mercuric chloride poisoning, mercury binds to the sulfhydryl groups of various cell membrane proteins, causing inhibition of ATP-dependent transport and increased membrane permeability.
Robin’s Textbook of pathology 10th edit Page 45