Which type of cloud is most likely to produce rain?

Cumulus clouds are large and lumpy. Their name comes from the Latin word meaning "heap" or "pile." They can stretch vertically into the atmosphere up to 39,000 feet high. Cumulus clouds are created by strong updrafts of warm, moist air. Most forms of heavy precipitation fall from cumulus clouds. The weather they bring depends on their height and size. The higher the base of a cloud is, the drier the atmosphere and the fairer the weather will be. Clouds located close to the ground mean heavy snow or rain.

Source: National Geographic