The correct answer is A. MH.
Inorganic soils with low compressibility are represented by the symbol MH. These soils are composed of silt and clay particles, and they have a high liquid limit and a low plasticity index. This means that they are able to hold a lot of water without becoming too loose, and they are not easily deformed when pressure is applied.
The other options are incorrect because they represent soils that are more compressible. Soils with the symbol SL are composed of silt and sand particles, and they have a low liquid limit and a high plasticity index. This means that they are not able to hold a lot of water without becoming too loose, and they are easily deformed when pressure is applied. Soils with the symbol ML are composed of silt and clay particles, and they have a medium liquid limit and a medium plasticity index. This means that they are able to hold a moderate amount of water without becoming too loose, and they are not easily deformed when pressure is applied. Soils with the symbol CH are composed of clay particles, and they have a high liquid limit and a high plasticity index. This means that they are not able to hold a lot of water without becoming too loose, and they are easily deformed when pressure is applied.