The highest concentration of carbon dioxide (CO2) in the body is found in d) the tissue cells.
Explanation: Carbon dioxide is a waste product of cellular respiration, a process where cells generate energy by converting glucose and oxygen into energy, water, and carbon dioxide. As the cells metabolize nutrients for energy, they produce CO2 as a byproduct, leading to a higher concentration in the tissue cells compared to other areas like the pharynx, trachea, alveoli, or larynx.
While the alveoli have significant concentrations of CO2 as they participate in gas exchange, the primary site for the highest levels of CO2 is actually within the tissue cells, where it is generated. In contrast, the pharynx, trachea, and larynx are part of the airway and contain much lower concentrations of carbon dioxide since they serve primarily as passageways for air to enter and exit the lungs.