Not only do deep-sea divers risk nitrogen narcosis, often called "raptures of the deep", if they descend below 200 feet, but they also fall prey to decompression sickness, commonly known as the "bends", if they ascend too quickly.

A] Not only do deep-sea divers risk nitrogen narcosis, often called "raptures of the deep", if they descend below 200 feet, but
B] Not only does a deep-sea diver risk nitrogen narcosis, often called "raptures of the deep", if they descend below 200 feet, but

[spoiler]OA: A
Source: Kaplan[/spoiler]