Answer:
A. Mobility
Explanation:
That Organism is a Prokaryote, The strings behind it helps the organism move around. If it didn't had those strings, the prokaryote would float around and it would have a hard time finding food to consume and survive.
I believe its D. It becomes more difficult for the cell to get enough oxygen and nutrients.
The answer is Natural selection Hope it Helps
Lining the thoracic cavity
