Researchers are studying how rapidly a hungry pigeon in a confined cage will learn to peck at a lighted disk in order to receive food. The researchers are most clearly using a(n) to study learning.

operant chamber                                                

Explanation:

Operant chamber: In psychology, the operant chamber was developed by one of the most influential psychologists and behaviorists named B. F. Skinner in order to abet with the "laboratory analysis" of specific animal behaviors.

An operant chamber is considered as a box that significantly holds or carries out an animal (rat or mouse), test subjects and is generally light and sound proof in order to restrict different responses from unexpected stimuli.

In the question above, the researchers are most clearly using an operant chamber to study learning.

answer is b.shrapnel