Movement of the chromosomes during anaphase would be most affected by a drug that prevents which events in mitosis and cell division?

Shortening of microtubules

Explanation:

Anaphase is the phase of mitosis which involves following steps:

Shortening of kinetochore microtubules. Movement of daughter chromosomes to poles. Forces generated mainly at kinetochores.

Sliding force is generated between interpiolar microtubules from opposite poles to pull the poles apart.

Movement of the chromosomes during anaphase would be most affected by a drug that prevents shortening of microtubules in mitosis and cell division as it is the first and foremost step of the anaphase. If this step is inhibited, other steps are also inhibited.