A large cavity or sac that is found in plant cells protozoans and contains air partially digested food?

The correct answer is vacuole. Vacuoles are large cavities or sacs that are found in plant cells, protozoans, and some other organisms. They are enclosed by a membrane and can contain air, partially digested food, water, or other materials. In plants, vacuoles help to maintain the cell's shape and turgor, and they also play a role in storage and transport of materials. In protozoans, vacuoles can help with digestion, excretion, and osmoregulation.