Which combination of weather-producing variables would likely result in cumuliform-type clouds, good visibility, and showery rain?

The combination of unstable, moist air and orographic lifting is ideal for the formation of cumuliform-type clouds, which are typically associated with good visibility and showery rain. When air is unstable, it tends to rise, creating vertical development. Moist air provides the necessary moisture content for cloud formation, while orographic lifting occurs when air is forced to rise over a mountain or elevated terrain. As the air ascends, it cools and condenses, leading to the development of cumuliform clouds, such as cumulus or cumulonimbus, which can produce showers or thunderstorms.

In contrast, stable air environments, whether they are dry or moist, typically do not allow for the vertical development of clouds, resulting in more stratiform cloud types that are generally associated with steady precipitation rather than showery rain. High-pressure systems often lead to clearer skies with limited cloud development, which would not produce the conditions described in the question. Thus, the combination in the correct choice captures the dynamic processes leading to the desired weather phenomena.