The absorption of ink by blotting paper primarily involves which of the following phenomena?

Given below are two statements, one labeled as Assertion (A) and the other as Reason (R): Assertion (A): A considerable amount of water is retained in the soil due to capillary action. Reason (R): Water exhibits high surface tension compared to most other common liquids. In light of the above statements, choose the correct answer:

On a clean glass plate, a drop of water spreads to form a thin layer whereas a drop of mercury remains almost spherical. This is because: