Which rock formation is least likely to contain water?

Granite is primarily composed of interlocking crystals of quartz, feldspar, and mica, which results in a very dense and impermeable rock. Because of its crystalline structure, granite does not easily allow water to permeate through it. Consequently, it is typically considered a poor aquifer, meaning it is least likely to contain significant amounts of water compared to the other materials listed.

In contrast, basalt, limestone, and sandy soil can all contain and transmit water more effectively. Basalt, while dense, can have weathered zones where water can accumulate, and it may also contain fractures that can hold water. Limestone is known for its ability to store water due to its formation of karst landscapes, which features cavities and channels formed by dissolution. Sandy soil is often very porous, allowing water to filter through easily and typically holding water in the spaces between the sand grains.

Therefore, granite’s geological characteristics make it the least likely to serve as a source of water compared to the other formations presented in the question.