Consider the following statements: Statement I: In the context of effect of water on rocks, chalk is known as a very permeable rock whereas clay is known as quite an impermeable or least permeable rock. Statement II: Chalk is porous and hence can absorb water. Statement III: Clay is not at all porous. Which one of the following is correct in respect of the above statements?

Statement I: Correct. Chalk is highly permeable because it is porous and also well-jointed, allowing water movement; clay is generally very impermeable or least permeable.

Statement II: Correct. Chalk is porous, so it can absorb/store water; this helps explain why it is associated with high permeability.

Statement III: Incorrect. Clay is porous in the sense of having tiny pore spaces, but those pores are very small and poorly connected, so water does not pass through easily; hence clay is impermeable, not non-porous.

Conclusion: Only Statement II is correct, and it explains Statement I. Hence (c).