When blood from the heart enters the capillaries surrounding muscles in the legs, which of following take place? A) Increased CO2 concentrations in blood cause CO2 to enter muscles.
B) Increased CO2 concentrations cause oxygen to enter the blood.
C) Diffusion causes oxygen molecules to enter muscle cells.
D) Diffusion of oxygen molecules occurs in and out of the muscle cells.

is D

Explanation:

the function of the protein macromolecule is to move things in and out of the cell and transport other molecules in the body. there are many functions of proteins. they are the basic building blocks of living things and are responsible for the growth and repair of body cells and tissues.

explanation:

satellites are frequently used to make observations of the orbit on earth