Red Blood Cells i believe are not part of the immune system. They carry oxygenated blood to the organs of the body
I believe it’s D sorry if i’m wrong!
<span>When you start a fitness program you are more motivated, you want to achieve your goals.Sometime achieving your goals may take time and this may affect your motivation, as you don't see the results as fast as you want. you lose your motivation and become more exhausted that's why it's easier to start fitness program than to maintain it. </span>