Answer:
Chemosynthesis
Step-by-step explanation:
All organisms make food either through photosynthesis or Chemosynthesis
.In this case bacteria are creating sugar (food) through all the course of activities mentioned here. Bacteria that live deep under the ocean uses energy released by any chemical reaction to make food (sugar) for themselves.
The chemical reaction involved here is as follows -
CO2 + 4H2S + O2 -> CH20 + 4S + 3H2O