Question

The following question has two parts. First, answer Part A. Then, answer Part B.

Part A:

Which sentence best states the central idea of the passage?

A.
Explorers rely on lighting to traverse dark caverns, and light can come from a variety of sources.

B.
Lighting can be a life-saving tool, and sometimes the brain creates an unexpected light source for that purpose.

C.
Glowworms are just one source of illumination for cave explorers in New Zealand and other inspiring places.

D.
The brain cannot be trusted to lead explorers through the darkest of caverns: explorers need sources of light.

Multiple Choice Question
Part B:

Which detail from the passage best supports the answer to Part A?

A.
Cavers consider such LED units to be lifesaving pieces of equipment that help them find their way out of a cavern. (paragraph 2)

B.
And while spelunkers would never rely on glowworms as a light source for exploring deep caverns, the bugs draw explorers . . . . (paragraph 3)

C.
. . . the brain thinks it sees its own body’s movement in spaces completely devoid of light. (paragraph 4)

D.
How explorers see in these dark spaces may be a matter of technology, biology, or curious tricks of the mind. (paragraph 5)

Answer 1

Part A: A

Part B: D

Explanation: The passage’s main idea is that explorers need light and that that light can come from different sources; sentence D (“How explorers see in these dark spaces may be a matter of technology, biology, or curious tricks of the mind.”) explicitly supports that central idea.