Which of the following is an incorrect statement? A. Gastrovascular cavities have a single opening through which animals both ingest food and expel wastes. B. Extracellular digestion is the process in which food is broken down outside cells in a digestive system. C. Intracellular digestion happens when animals digest food inside specialized cells that pass nutrients to other cells by diffusion. D. Digestive tracts have 2 openings, which allows food to move in 2 directions.

The digestive system is a long twisted tube from the mouth to the anus with a series of accessory organs connected to it. This long twisted continuous tube having two openings, mouth and the anus, called the digestive tract that allows food to move in one direction only (mouth to anus).

In the digestive tract, food enters from the mouth and food passing through pharynx, esophagus, stomach, small intestine, and large intestine. The indigestible food or waste eliminated through the anus.

So, the digestive tract allows food to move in one direction only.

Thus, incorrect option would be option D.