Jamal drew a flow chart to show how the carbon in his brain tissue originated as co2 in the atmosphere. interpret his model.

We have heard about Respiration. In human beings, respiration is a cellular activity which takes place in the presence of oxygen and in result produces carbon dioxide. Jamal model is a clear manifestation of that process. Medulla is the region of a brain that controls the respiration activity. When we breathe we take in oxygen and the excess amount of carbon dioxide is removed from out body.

Brains cells have capability to detect the carbon concentration in blood and add excess amount of carbon from body to the air.  

your answer should be c) enjoy!