Answer:
D.
Have a wonderful day, and good luck!
Oxygen-poor blood enters the heart through the right atrium. From there blood flows through the tricuspid valve into the right ventricle. When the heart contracts during the diastolic phase, this blood is pumped out through the pulmonary arteries that run toward the lungs. At the lungs, the blood is circulated through a series of progressively smaller arterioles until it flows through capillaries lining the lungs' alveolar sacs. It is here that gas exchange takes place as oxygen is taken up by the blood, and carbon dioxide is released into the waste air.After oxygenation, the fresh blood is circulated back through the bronchial veins and into the pulmonary veins. These run from the lungs and drain into the heart's left atrium. During the systolic phase of the heartbeat, the mitral valve under the left atrium opens and permits blood to pass into the left ventricle. This chamber is heavily muscled and it has the power to pump the oxygen-rich blood out through the aorta and into the rest of the body.
So, as you know, when a sperm cells (Male sex cell) meets the Egg cell (Female Sex Cell) it forms something called a zygote. And from that point on, the egg cell reproduces more and more (making more cells) in a type of cell called a stem cell, which can be used for anything the body needs. The newborn babies keep these cells up until birth or the incubation (growth of the baby in the mother's uterus), and then they are ready to be born.
I would say teh cytoplasm and nucleus.
