Answer: C. amount of rainfall
Step-by-step explanation:
The amount of rainfall is an abiotic factor (non-living) which is necessary for the growth of plants. The water from the rainfall is necessary for the large scale natural irrigation of an agricultural land, forest, meadow or grassland. The water enters into the soil and through the roots the water is absorbed by the plants.
If a region receives very low annual rainfall then the region may experience desertification. The soil will become compact and dry which cannot support the growth of plants.
If a region receives adequate rainfall then the soil will hold water it will remain fertile to support the diversity of plants.