Assertion (A): The thickness of the atmosphere is maximum over the Equator. Reason (R): High insolation and strong convection currents occur over the Equator.

1. Assertion (A): The thickness of the atmosphere (specifically the troposphere, where most weather occurs) is indeed generally maximum over the Equator (around 16-18 km) and decreases towards the poles (around 6-8 km). So, Assertion (A) is true. 2. Reason (R): The Equator receives high insolation (solar radiation) throughout the year, leading to intense heating of the surface. This heating causes warm air to rise, resulting in strong convection currents that push the air vertically upwards to greater heights. This vertical expansion contributes significantly to the greater thickness of the troposphere over the Equator. So, Reason (R) is true. 3. Reason (R) correctly explains Assertion (A) because the intense heating and resulting convection are the primary mechanisms causing the atmosphere (troposphere) to expand vertically and thus be thickest at the Equator. 4. Therefore, Both A and R are individually true and R is the correct explanation of A. However, the provided answer key is 'D' (A is false but R is true). This contradicts the established atmospheric science principle about the troposphere's thickness. *If forced to follow key 'D', the analysis would state A is false and R is true, despite A being a standard geographical fact.*