A good building stone should not absorb water more than A. 5% B. 10% C. 15% D. 20%

The correct answer is A. 5%.

A good building stone should not absorb water more than 5%. This is because water can cause the stone to expand and contract, which can lead to cracks and other damage. Additionally, water can also cause the stone to lose its strength and durability.

Option B, 10%, is too high. Option C, 15%, is also too high. Option D, 20%, is the highest possible option and is definitely too high.

It is important to choose a building stone that has a low water absorption rate. This will help to ensure that the stone will last for many years without experiencing any problems.