Answer, and give a reason. Why does a towel soak up water? …

Step 1. (a) The tiny gaps between the fibres act as capillary tubes, and water, which wets cotton, climbs into them.

Step 2. (b) The upward pull goes as the edge length, $2\pi r$, but the weight held up goes as $\pi r^2h$, so $h \propto \dfrac{1}{r}$.

Step 3. (c) Hoeing breaks up the fine channels near the surface, so water cannot climb up them and evaporate.