Step 1: Understanding contour lines in meteorology.
- Isohyet: Line connecting points of equal rainfall.
- Isotherm: Line connecting points of equal temperature.
- Isobars: Line connecting points of equal atmospheric pressure.
- Isopleth: General term for contour lines representing any other variable.
Step 2: Selecting the correct option.
Since the question asks about rainfall, the correct answer is a. Isohyet.