Answer:
C (An end product of normal cell metabolism)
Explanation:
All cells of living organisms engage in a metabolic (catabolic) process where they breakdown organic molecules to produce ATP, water and release Carbondioxide (CO2) as a waste product. This metabolic process is known as CELLULAR RESPIRATION.
Cellular respiration is the normal biochemical process all cells undergo to convert the high energy stored in their food source to a usable form (ATP). Since an organic compound (glucose) is broken down, the process releases CO2. It can occur with (aerobic) or without oxygen (anaerobic). The general equation for aerobic respiration is:
C6H12O6 + 6O2 ----> 6CO2 + 6H2O