On piles, the drop must be at least A. 80 cm B. 100 cm C. 120 cm D. 140 cm

The correct answer is: A. 80 cm.

The drop on piles is the distance between the top of the pile and the ground. It is important to ensure that the drop is at least 80 cm to prevent the pile from sinking into the ground. If the drop is less than 80 cm, the pile may not be able to support the weight of the structure that is being built on it.

Option B is incorrect because it is not the minimum drop required for piles. Option C is incorrect because it is not the minimum drop required for piles. Option D is incorrect because it is not the minimum drop required for piles.