The word that is different from the rest is D: Stethoscope.
Reasoning:
To identify the word that is different from the rest, we need to examine the characteristics of each word and look for any distinctive features or functions that set it apart from the others.
1. Microscope: A microscope is a scientific instrument used to observe objects that are too small to be seen by the naked eye. It magnifies and enhances the image of the specimen under observation.
2. Telescope: A telescope is an optical instrument used to view distant objects in space. It collects and focuses light to create a magnified image of celestial bodies such as stars, planets, and galaxies.
3. Periscope: A periscope is an instrument used for viewing objects or scenes from a concealed or elevated position. It consists of a tube with mirrors or prisms that reflect light, allowing the viewer to see over obstacles or around corners.
4. Stethoscope: A stethoscope is a medical device used by healthcare professionals to listen to the internal sounds of a patient's body, particularly the heart and lungs. It consists of a chest piece, tubing, and earpieces.
Conclusion:
While all the given options are instruments used for observation or examination, the stethoscope stands out as it is primarily used for medical purposes to listen to internal sounds rather than for visual observation.