Because the hydra has a nervous system characterized by a nerve net other than a cockroach
Mitochondria is the right one hope this helped you!
Answer:
Osmosis
Explanation:
In this case, osmosis has occurred, and that is why the movement of the flagellum stops.
It should be understood that osmosis is the movement of substances from the region of lower concentration to the region of lower concentration through a semi- permeable membrane.