This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
Which of the following is an inhibitor of RNA polymerase in eukaryotes ? 
Select and explain. 
A. Alpha-amanitin, B. Rifampicin, C. Both, D. None
A: Alpha-amanitin
Answer: A: Alpha-amanitin 
Explanation: RNA polymerase II enzyme is inhibited by a-amanitin in eukaryotes. a-amanitin is a potent toxin produced by the poisonous mushroom Amanita phalloides (sometimes called "death cap"). a-Amanitin forms a tight complex with the polymerase, thereby inhibiting mRNA synthesis and, ultimately, protein synthesis. Rifampicin inhibits the prokaryotic DNA dependent RNA polymerase Reference: Harpers illustrated biochemistry 30th edition