Colchicine inhibits the formation of microtubules by inhibiting tubulin, a protein required for microtubule synthesis. Microtubules in the form of spindle fibers during cell division pull the DNA from the center of the mother cell into the new daughter cells. If microtubules are not formed DNA will not move into new cells. Hence new cell formation will be inhibited in the metaphase stage. Thus the correct answer is option D.
