The first diagram shows a single-loop circulation, which is characterized by a single pump that moves the blood in a unidirectional flow. The heart has two chambers: an atrium and a ventricle. Once the heart receives the blood from the body capillaries through the atrium, the blood is pumped out of the heart and into the gill capillaries through the ventricle.

The second diagram shows a four-chambered heart–two atria and two ventricles. This circulatory system undergoes a double-loop circulation, which is characterized by a two-pump system. The first loop, which is located on one side of the heart, pumps oxygen-poor blood into the lungs. The second loop, which is on the other side of the heart, receives the oxygen-rich blood and pumps it into the rest of the body. through the systemic capillaries.

Therefore, B is the correct answer.

B. The heart of the circulatory system pumps oxygen-poor blood to the tissues of the respiratory system where the blood is oxygenated.

Choices A, B, C, and E are incorrect. The correct answer is D. Meat eaters have jaw bones and sharp teeth that are able to slice or tear the meat into small chunks. Their mouthpart, which is a part of their skeleton, starts the mechanical digestion. Then, it is followed by chemical digestion, wherein when the meat is broken down into simpler compounds with the help of digestive enzymes.

D. The jaw bones of the skeletal system are specialized to chop meat and begin the process of digestion.

Choices A, C, D and E are incorrect. Some animals immediately get rid of ammonia from their body by diffusion or excretion. However, for most animals that are not able to release nitrogen-wastes by diffusion, their kidneys filter the blood to get rid of the waste. Then, it is converted into urea and eliminated from the body as urine.

B. They are removed from the blood in the kidneys and excreted.