About vinca alkaloids true is

About vinca alkaloids true is ?
a) Inhibits mitotic spindle
b) Enhances polymerization of tubulin
c) Inhibits topoisomerase I
d) Inhibits topoisomerase II
Correct Answer - A
Ans. is ‘a’ i.e., Inhibits mitotic spindle
Vinca alkaloids (vincristine) inhibit mitotic spindles by preventing
polymerization of tubulin