Which relation between rainfall amount and soil water holding capacity is most important for plants?

Correct answer: How long rainfall water remains available in soil is important

Plants do not benefit only from the total amount of rain; they also need water to remain available in the soil for a suitable period. Soil texture, structure, depth, organic matter, and drainage influence how much water is stored and how quickly it is lost. A region with moderate rain and moisture-retaining soil may support vegetation better than a region with heavy rain that drains away quickly.

Option C is correct because it focuses on the duration of usable soil moisture. High rainfall alone is not always enough: intense rain may run off, evaporate, or drain below the root zone. Soil colour by itself does not determine plant water supply, and water-holding capacity has clear meaning for roots. Thus, rainfall amount and the soil’s ability to retain water must be considered together.