Answer: b-respiration
Step-by-step explanation:
Producers are the organisms which can conduct photosynthesis which is the process through which green plants and other autotrophs can produce their own food by utilizing carbon dioxide and water in the presence of sunlight.
These organisms also perform a metabolic process that is named as respiration. The producers take up oxygen from the environment which can be utilized to break down the food in the form of glucose into simple substances along with the release of energy and carbon dioxide as a metabolic waste.