Final answer:
The trend shown in the illustration is that as elevation increases, temperature decreases (option D). This affects vegetation types, leading to distinct zones like tundra, coniferous, deciduous, and tropical forests at different elevations.
Step-by-step explanation:
The correct answer to the student's question about the trend shown in the illustration regarding elevation zones and glacier vegetation types is D.
As elevation increases, temperature decreases. This is a fundamental concept in geography and relates to the lapse rate, which is a measure of how temperature changes with a change in altitude. In general, this rate is around 3.5 °F for every 1,000 feet of elevation gained.
This trend affects the types of vegetation that can grow at higher elevations, leading to distinct vegetation zones such as tundra, coniferous and deciduous forests, down to tropical forests as you descend.
As one moves up a mountain or towards higher latitudes, changes in vegetation occur that are similar to those found as you move from the equator to the poles.
You see a progression from tropical forests with high biodiversity near the equator through temperate deciduous forests, coniferous forests or taiga, and eventually to the Arctic tundra, which is characterized by sparse vegetation due to severe cold.