The correct answer is: B. different for different types of soils and also different for a soil under different states of consolidation.
The coefficient of compressibility is a measure of how much a soil will compress under a given amount of stress. It is different for different types of soils because different soils have different properties, such as particle size, shape, and mineralogy. The coefficient of compressibility is also different for a soil under different states of consolidation because the soil will compress more or less depending on how much stress it has already been subjected to.
Option A is incorrect because the coefficient of compressibility is not constant for any type of soil. Option C is incorrect because the coefficient of compressibility is not the same for a soil under different states of consolidation. Option D is incorrect because the coefficient of compressibility is not independent of the type of soil.