Choose the word which is different from the rest.

Microscope
Telescope
Periscope
Stethoscope

The answer is D. Stethoscope.

A microscope is an instrument used to magnify small objects. A telescope is an instrument used to make distant objects appear closer. A periscope is an instrument used to see above or around an obstacle. A stethoscope is an instrument used to listen to the sounds produced by the body, such as the heartbeat.

A stethoscope is different from the other three options because it is not used to see objects. It is used to hear sounds.