I believe its D. It becomes more difficult for the cell to get enough oxygen and nutrients.
Answer:
Proteins are large, complex molecules that play many critical roles in the body. They do most of the work in cells and are required for the structure, function, and regulation of the body's tissues and organs
Explanation:
Bone marrow plays an important role in our circulatory system because Bone marrow contains hematopoietic stem cells which is the major producer of red blood cells or erythrocytes,white blood cells also know as leukocytes and also platelets( thrombocytes) which is the major components of our blood,the only liquid that is very essential in our circulatory system.