Excretion removes metabolic wastes from the body

Steps:

• Define excretion as the elimination of harmful metabolic byproducts like CO2, urea, and excess salts.
• Evaluate each option against this definition, focusing on whether it involves waste removal.
• Identify B as matching the removal of CO2, a key metabolic waste via lungs.
• Confirm B by excluding non-waste processes like secretion or egestion.

Why B is correct:

• Excretion includes lungs expelling CO2, a waste from cellular respiration, as per biological definitions of waste elimination.

Why the others are wrong:

• A: Hormone release is endocrine secretion, not waste removal.
• C: Undigested food removal is egestion via feces, distinct from metabolic excretion.
• D: Sweat gland water release is thermoregulation, not primarily metabolic waste excretion.

Final answer: B