Answer: B - transports oxygen and carbon dioxide for the respiratory system
The cardiovascular system consists in the heart and all blood vessels. Blood vessels lead the blood from the heart to the rest of the body and then brings it back. It's in the lungs, part of the respiratory system, where the gas exchange is going to happen. What that means is that oxygen is going to enter the blood while the carbon dioxide needs to be eliminated.
(If the option A, said carries hormones FROM the endocrine system, that would be also correct.)