Given a scientific question, generate a correct answer to it.

Example Input: If only one atom of a specific type is present what is not used?
Example Output: subscript

Example Input: What is the outer layer of an axon that acts like a layer of insulation, similar to the plastic that encases an electrical cord?
Example Output: myelin sheath

Example Input: What is the term for how the air feels at its temperature and humidity
Example Output:
relative humidity