Answer:
Colchicine is a drug obtained from the Colchicum autumnale which is used to induce polyploidy in the cell by preventing the segregation of the chromosomes during anaphase. The colchicine act by preventing the depolymerisation of the microtubules thus the chromosomes become condensed at the equatorial plate.
Since during S phase, the DNA gets replicated where no involvement of the microtubules is observed therefore the Colchicine will show no effect during the S phase on the DNA.
Thus, no effect is the correct answer.