Answer:
In Branchiostoma, it is used mainly for feeding. The pharynx consists of numerous pharyngeal bars, with pharyngeal slits between them. The animal sucks in water through its mouth and forces it out through the pharyngeal slits, capturing small food particles from the water
The answer is A. I'm sure about this
I am assuming that since you are in a biology class, you are looking for the answer: cells.
Hope this helps! <3
