If a cell is treated with drugs such as Colchicine, vincistrine, the assembly of the microtubules is inhibited, while the dis-assembly continues leading to continues disorganization of microtubules. Colchicine is an alkaloid. It can be extracted from corms of plant Colchicum autumnale and C. luteum. Colchicines prevent spindle formation during mitotic metaphase. Thus, it prevents the separation of chromosomes during anaphase stage. Hence, the correct answer is option B.