The correct answer is C. Incoming solar radiation.
Insolation is a measure of the solar radiation that is received by a surface per unit area. It is usually expressed in units of watts per square meter (W/m2). The amount of insolation that a surface receives depends on a number of factors, including the angle of the sun’s rays, the amount of cloud cover, and the presence of any obstructions such as trees or buildings.
Insolation is an important factor in determining the climate of a region. It is also used in the design of solar energy systems.
A well-constructed, energy-efficient home is not directly related to insolation. The solar constant is the average amount of solar radiation that is received by the Earth’s atmosphere per unit area. An increase in solar output is not the same as insolation.