What is the main difference between cumulus and stratus clouds concerning moisture?

The distinction between cumulus and stratus clouds primarily relates to their physical structure and the moisture they hold. Cumulus clouds, characterized by their fluffy, cotton-like appearance, tend to be thicker and can develop vertically. This vertical growth is associated with rising air currents, which leads to condensation and, in many cases, precipitation.

On the other hand, stratus clouds are typically thin and layered, appearing as a uniform blanket in the sky. They generally form when a mass of cooler air blankets a flat, stable area, leading to gradual condensation without the vertical development seen in cumulus clouds. Stratus clouds can produce light precipitation but are less likely to result in significant rainfall compared to cumulus clouds.

Therefore, the principal difference lies in the thickness and structure of the clouds: cumulus clouds, being thicker and often precipitation-prone, contrast with the thin, layered nature of stratus clouds. This understanding illuminates why option A correctly describes the relationship between these two types of clouds regarding moisture involvement.