One of the Main Reasons That We Exhale a Higher

One of the main reasons that we exhale a higher percentage of carbon dioxide than we inhale is,

A) we use carbon dioxide to make glucose.
B) we produce carbon dioxide as a by-product of aerobic respiration.
C) we produce carbon dioxide as a by-product of transmission of nerve impulses across synapses.
D) carbon dioxide is a by-product of photosynthesis.
E) carbon dioxide dissolves better in blood than does oxygen.