Propose a question that a scientist might ask about the variety of organisms found around deep sea vents.

The answer is do all of these organisms use chemosynthesis.

Chemosynthesis is a process in which some bacteria produce sugar, similarly to photosynthetic process. But, while in photosynthesis the energy of Sunlight is used to convert carbon dioxide and water into sugar and oxygen, in chemosynthesis, carbon dioxide, oxygen, and hydrogen sulfide are used to produce sugar, along to water and sulfur. This process is preferable when there is no light and the environment is rich in sulfide or methane, such in deep sea vents. 
Thus, to asses the variety of organisms found around deep sea vents, it should be researched if all organisms use chemosynthesis, or maybe some other process.