They work together to exchange gases. They work together to transport nutrients. They work independently to remove wastes. They work independently to relay messages.
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Arteries and veins are two important parts of the circulatory system. What is the relationship between arteries and veins?
Possibilities:
- They work together to exchange gases.
- They work together to transport nutrients.
- They work independently to remove wastes.
- They work independently to relay messages.

They work together to transport nutrients.