The answer would be <span>B) </span>Sternomastoid and trapezius :)
The structure shown by the red arrow is cell membrane.
In biology, cell membrane refers to the thin layer, which develops the external boundary of a living cell. It has three primary functions, which are as follows:
1. It comprises channels and receptors, which permits particular molecules like nutrients, ions, metabolic components, and wastes to pass between the cell and the outside environment.
2. It prevents toxic components from entering the cell.
3. They distinguish essential but incompatible metabolic procedures conducted within the cell.
B. One
because an independent variable is something you change. So in a scientific experiment you only change one thing. If you happen to change more than one thing then the test becomes unfair therefore you should repeat and make sure that only one thing is changed this time.
