The Answer to this question is b
Answer:
They have a closed circulatory system.
Explanation:
In an open circulatory system, blood vessels transport all fluids into a cavity. When the animal moves, the blood inside the cavity moves freely around the body in all directions.
Closed circulatory systems are different to open circulatory systems because blood never leaves the blood vessels. Instead, it is transferred from one blood vessel to another continuously without entering a cavity.
When testing a hypothesis, scientists use repeated trials and replication to make sure that they get the same answer each time, and that it isn't just a lucky guess the first time. They need be sure that the answer to their hypothesis is 100% the same every time.
No because if your body has never experienced it before it will not no what to do and most likely the body will just send out/produce the other common antibodies or cells
