Which statement shows that vegetation is not controlled by a single factor?

Correct answer: Despite equal rainfall, vegetation may change if soil and temperature differ

The direct answer is A: even with equal rainfall, vegetation may change when soil and temperature differ. Vegetation is not decided by rainfall alone. Plants need water, but they also need suitable temperature, soil type, sunlight, relief, and sometimes human land use. Step by step: imagine two places receiving the same amount of rain; if one has fertile, deep soil and the other has thin, salty, or sandy soil, their plants may differ; if their temperatures also differ, plants suited to one place may not grow well in the other; therefore vegetation changes because several factors interact. Option A is correct because it gives a clear example of combined control. Option B is wrong because rainfall is important but not the only controlling factor. Option C is wrong because soil and temperature strongly affect germination, growth, and plant distribution. Option D is wrong because farming, cutting forests, grazing, and construction can greatly change natural vegetation. The memory cue is “vegetation equals climate plus soil plus relief plus human influence,” not rainfall alone.