Answer:
The correct answer is option A, reservoir
Step-by-step explanation:
All the plant, animals, and all other biomass is predominantly made up of carbon and are found mainly in the ocean reservoir, lithosphere and atmosphere . Also all the plants either on land or in ocean entraps the nutrients (i.e carbon, nitrogen etc.) from surroundings through photosynthesis and convert them into energy rich molecules which also get concentrated in the ocean reservoir, lithosphere and atmosphere. These three spheres are called the reservoirs as they contain 100% of the nutrients (including carbon) with in them .