The correct answer is option 1: Volcanic.

The Comoros Islands, located in the Indian Ocean between Northern Madagascar and the African Coast, are classified as volcanic islands. Volcanic islands are formed through volcanic activity, where magma rises to the surface and solidifies, creating new land. This process usually occurs at subduction zones, where there is a convergent boundary between two tectonic plates.

In the case of the Comoros Islands, they were formed as a result of volcanic eruptions that took place millions of years ago. The islands are part of a volcanic archipelago known as the Comoros hotspot, which is still considered to be an active volcanic area.

These volcanic islands often have distinct features, such as rugged terrain, steep slopes, and volcanic rock formations. They may also have fertile soil, as volcanic ash and lava can provide nutrients for plant growth.

In summary, the Comoros Islands are categorized as volcanic islands due to their formation through volcanic activity.