The excretory system the respiratory system by
• introducing more oxygen into the lungs
• circulating blood into and out of the lungs
• removing carbon dioxide that is produced during respiration
• removing urine that is produced during respiration

The correct answer would be "removing carbon dioxide that is produced during respiration".

An excretory system with the help of circulatory system removes the carbon dioxide produced as a result of cellular respiration.

The carbon dioxide produced in a cell is converted to carbonic acid with the help of carbonic anhydrase. The carbonic acid is then transported to the lungs in a dissolved form with the help of the blood.

At the alveolar site, the carbonic acid is converted back to carbon dioxide with the help of same enzyme carbonic anhydrase. The carbon dioxide is then excreted out with the help of the lungs.

only about ten percent of the energy at one trophic level is passed on to organisms at the next trophic level. the remainder of the energy is used in life processes or lost as heat.