Someone please help I took the picture this is my last question on my homework

According to the image that represents a cell in the human body, the true statement is that structure 4 is the cell membrane that provides exchange of O₂ & CO₂.

Explanation:

In cells, the cell membrane acts as a semi-permeable barrier to the passage of substances, including nutrients and oxygen (O₂).

One of the functions of the cell membrane is to allow the exchange of O₂ —necessary for the cell— and carbon dioxide (CO₂), a product of cell metabolism that must be removed.

In the image, the structure identified with the number 4 corresponds to a cell membrane of human cells that provides this gas exchange.

The other options are not correct because:

the index of refraction of the second medium is higher. i just took the test trust me !