Final answer:
The low-lying Caribbean islands like the Bahamas were formed by coral reefs rising above the ocean surface, whereas tectonic activity, including earthquakes and volcanic activity, contributes to the formation of the mountainous regions in other parts of the Caribbean.
Step-by-step explanation:
The flatter, sandier, low-lying Caribbean islands were formed primarily through the action of coral reefs rising above the ocean surface, rather than tectonic activity, glacial activity, erosion, or volcanic activity directly creating the sand and land masses. These islands, such as the Bahamas, are characterized by their flat terrain and sandy beaches, which distinguish them from other Caribbean islands that have undergone different geological processes such as tectonic plate collisions, leading to mountain formation and volcanic activity, which are phenomena more common in shaping the high-elevation and mountainous islands of the region.
Tectonic plate activity does play a significant role in the broader geological dynamics of the Caribbean, contributing to earthquakes and the existence of mountainous terrain in other parts of the region. This activity can result in mountain ranges with peaks reaching significant elevations, as seen in the varied physical geography across the Caribbean. However, the specific features of the flatter, sandier, low-lying islands are more aptly associated with the growth and development of coral reefs.