Context: Read the text.
Most animals need to maintain a body temperature within a narrow range. Endotherms, such as humans and other mammals, can regulate their temperatures internally. When the temperature of their surrounding environments changes, endotherms may shiver or sweat to keep their body temperatures within a normal range.
For ectotherms, by contrast, a change in the temperature of the surrounding environment will usually affect the animal's body temperature. Ectotherms often regulate their body temperatures by moving within their environments; for instance, a lizard will lie out in the sun to warm itself up.
Which term matches the picture?
A. endotherms
B. ectotherms
From the given choices, pick the correct answer and respond by indicating the letter of the correct option.

A