Explanation:
Colchicine is a microtubule specific drug whereas cytochalasin is a drug that blocks polymerization of actin filament and blocks cell division in animals
Colchicine tightly binds with free tubulin dimer and prevent its polymerization, in this case mitotic spindle apparatus does not assemble (disappear) and cell unable to do partitioning of chromosomes into two groups and thus arrest cell division
If cell is disrupted by colchicine but not by cytochalasin, cell division will be arrested and cell process will not occur