I’m pretty sure it’s d hope that helped
Answer:
Option D, has only a single opening
Explanation:
A gastrovascular cavity has only one opening. The food goes in and comes out of the same opening there by making it a two way digestive tract.
However, a digestive tube is a one way digestive tract where the food goes in from mouth (one end) and comes out of anus (second end) . It is also called as alimentary canal
Hence, option D is correct
The answer is b considering that the cell is a basic structure for organisms and yeah hope that helps and provides a strong backbone to my answer