Question

For plants inhabiting a tropical rainforest, the critical competition, is for-
A. Soil nutrients
B. Water
C. Space
D. Light

Answer 1

Hint: Tropical rainforests stand out not only for their astounding biota diversity but also for the intricate relationships between all of the plant and animal life that has coevolved there over millions of years.

Complete step by step solution:
The structure of the tropical rainforest is extremely intricate. Its diverse vegetation serves as an example of the fierce competition for light that exists in this climate when other climatic parameters are non-limiting at any time of year, allowing the vegetation to reach an unmatched luxuriance and biomass.

Few plants can survive in the dark environment below ground, and instead of little herbaceous plants, the surface is distinguished by a covering of rapidly decomposing dead leaves.

Plants in tropical rainforests struggle fiercely for light above ground, and below ground, they do the same.

The majority of plants rely on light to meet their energy needs; in their chlorophyll-rich green tissues, photosynthesis transforms light energy into chemical energy in the form of carbohydrates. Few plants can survive in the dark environment below ground, and instead of little herbaceous plants, the surface is distinguished by a covering of rapidly decomposing dead leaves. Although there are a few forbs like ferns and gingers and mosses that grow on tree butts, the ground is often devoid of living vegetation, and even bushes are uncommon.

So, the correct answer is option D, Light.
Note:
In addition to lesser plants like algae, mosses, and lichens, epiphytes are exceptionally diverse and include huge plants like ferns, orchids, aroids, and bromeliads. Epiphytes are frequently so numerous in tropical rainforests that their weight topples trees.