The movement of substances across the cell membrane either into or out of the cell
The answer is C, because it has a negative charge -1. All groups with charges called ions, unless they are organic compounds.
The elodea is getting the carbon dioxide from its environment like when underwater animals breathe out carbon dioxide the plants will use that carbon dioxide. The plants can also get the carbon dioxide from the atmosphere which can "dissolve" in water.
The correct option is D.
Cellular respiration is the process by which the body breaks down the sugar molecules that are eaten in food with the aid of oxygen and covert them into energy, carbon dioxide and water are also produced as by products. Cellular respiration and fermentation are both involved in the breaking down of sugars but cellular respiration occurs in the presence of oxygen while fermentation occurs in the absence of oxygen. Carbon dioxide is breath out by the lungs during cellular respiration.