Question

Which passage from the article best supports the idea that the Vermilion rainforest covers a large area of land?

Elrick and other researchers discovered the forest in the early 2000s. They drove deep underground into the mines in armored vehicles. Then they walked along miles of seven-foot-high (2.1-meter-high) passages.
The rainforest is more than 200 feet (61 meters) below ground. It is just above the Riola and Vermilion Grove coal mines. The forest dates back 307 million years to the ancient Pennsylvania Age.
Elrick and the other researchers continued documenting what was above the Vermilion County mines. They drew and took pictures. They made notes. They also studied slabs of rock taken from the mine.
It was alive during the Pennsylvania Age. That's when vast rainforests, swamps, and deltas covered much of the eastern and midwestern U.S.

Answers

GPT-4o mini
The passage that best supports the idea that the Vermilion rainforest covers a large area of land is:

"It was alive during the Pennsylvania Age. That's when vast rainforests, swamps, and deltas covered much of the eastern and midwestern U.S."

This sentence indicates that the rainforest was part of a broader ecosystem that extended over a significant portion of land in the eastern and midwestern United States, implying its large area.