I believe the answer is D) ATP is too unstable
It enters the heart via the pulmonary veins
Answer:
The cardiovascular system pumps blood from the heart to the lungs to get oxygen. The heart then sends oxygenated blood through arteries to the rest of the body. The veins carry oxygen-poor blood back to the heart to start the circulation process over.
is that the full answer or are there choices as well because that could make this easier to answer.
