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: Pharmacology
About vinca alkaloids true is ? 
Select and explain. 
A. Inhibits mitotic spindle, B. Enhances polymerization of tubulin, C. Inhibits topoisomerase I, D. Inhibits topoisomerase II
A: Inhibits mitotic spindle
Answer: A: Inhibits mitotic spindle 
Explanation: Ans. is 'a' i.e., Inhibits mitotic spindle Vinca alkaloids (vincristine) inhibit mitotic spindles by preventing polymerization of tubulin