Concept:An isotherm is a line drawn on a map to connect places that have equal temperature.
Explanation:The word "isotherm" is made from "iso-" meaning equal and "therm" meaning heat or temperature.
So an isotherm joins all points that record the same temperature at a particular time.
It is a common tool used on weather maps to show the distribution of heat across a region.
Lines joining places of equal pressure are called isobars, while lines joining places of equal rainfall are called isohyets.
Thus, the term "isotherm" specifically refers to equal temperature, not cloud cover, pressure, or rainfall.
Answer:D. Temperature