This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cytotoxic Anticancer Drugs, Subject name: Pharmacology
All of the following statements about methotrexate are true EXCEPT: 
Select and explain. 
A. It is cell cycle specific and kills cells in the S phase, B. Its toxicity primarily affects bone marrow and epithelial structures, C. Folic acid reverses its toxic effects, D. It is the drug of choice for choriocarcinoma
C: Folic acid reverses its toxic effects
Answer: C: Folic acid reverses its toxic effects 
Explanation: Folinic acid (leucovorin) is used to reverse the adverse effect of methotrexate. Folic acid is ineffective. All other statements are true