Exp) Option c is the correct answer.

Option a is incorrect:  While it is true that the equator receives more direct sunlight compared to the poles, the actual difference in insolation is not as large as ten times. The difference in insolation between the equator and poles is primarily due to the curvature of the Earth and the tilt of its axis, resulting in varying angles at which sunlight reaches different latitudes.

Option b is incorrect:  Insolation refers to the total solar radiation received at the Earth’s surface, which includes a broad spectrum of electromagnetic radiation. While infrared radiation is a significant component of solar radiation, it does not account for two-thirds of the insolation. Insolation includes visible light, ultraviolet (UV) radiation, and other wavelengths as well.

Option c is correct:  Water vapor is a potent absorber of infrared radiation, particularly in certain wavelength bands. In the lower atmosphere, where water vapor concentration is relatively higher, it absorbs a significant amount of infrared radiation emitted by the Earth’s surface. This absorption contributes to the greenhouse effect and plays a crucial role in regulating the Earth’s temperature.

Option d is incorrect:  Infrared waves and visible light waves are distinct parts of the electromagnetic spectrum. The visible spectrum ranges from approximately 400 to 700 nanometers and includes the colors we perceive, such as red, orange, yellow, green, blue,

and violet. Infrared radiation, on the other hand, has longer wavelengths than visible light and is not visible to the human eye. It lies just beyond the red end of the visible spectrum and is typically divided into near-infrared, mid-infrared, and far-infrared regions based on wavelength.

Source:  https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2005JD006796

https://www.ces.fau.edu/nasa/module-2/how-greenhouse-effect-works.php

http://www.soest.hawaii.edu/mguidry/Unnamed_Site_2/Chapter%202/Chapter2B2.html

Subject) Geography & Environment