Chameleons are tree-dwelling lizards known for their ability to change body color. Most are 7–10 inches long and have big, bulgy eyes. Chameleons can turn various shades of green, yellow, cream, or dark brown, sometimes with spots. It is a common misconception that they change color to match the background; really, they change because of light, temperature, or a change in emotion.

What is the main idea of the paragraph?

A.
Chameleons are lizards known for their ability to change colors.

B.
Chameleons change color because of light, temperature, or a change in emotion.

C.
It is a common misconception that chameleons change color to match their background.

D.
Most chameleons are 7–10 inches long and have big, bulgy eyes.

The main idea of the paragraph is given as the most important and central thought, the point of the paragraph. These are usually introductory sentences, but it's not always the case. You should pay attention to what is said in the paragraph. In this case, the paragraph is open with the description of chameleons, according to their ability to change body color. The other sentences provide additional different information that complements the main idea, the different characteristics of chameleons and some of the misconceptions associated with them.

The answer is: Chameleons are lizards known for their ability to change colors.