They both bring oxygen to the body. They both send messages to the body. They both digest nutrients for the body. They both pump blood through the body.
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Kendall studied the ways in which human body systems work together. He compared the respiratory and circulatory systems. In which way are these two systems similar to each other?
Possibilities:
- They both bring oxygen to the body.
- They both send messages to the body.
- They both digest nutrients for the body.
- They both pump blood through the body.

They both bring oxygen to the body.