What type of cloud is typically associated with severe thunderstorms?

Cumulonimbus clouds are the correct answer due to their association with severe thunderstorms. These clouds are characterized by their towering structure, which can reach high altitudes and have significant vertical development. They are capable of producing intense weather phenomena such as heavy rain, hail, lightning, and tornadoes.

The development of these clouds is often linked to strong updrafts and instabilities in the atmosphere, which contribute to their robust nature. Cumulonimbus clouds can also extend into the stratosphere, where conditions can intensify the weather events associated with them.

In contrast, stratus clouds are typically associated with overcast skies and light precipitation, cirrostratus clouds often indicate the approach of a warm front with gentle rain, and altostratus clouds usually suggest stable conditions with little severe weather potential. Thus, they are not linked to the severe conditions that cumulonimbus clouds can produce.