What type of circulatory stay do humans have

While humans, as well as other vertebrates, have a closed blood circulatory system (meaning that the blood never leaves the network of arteries, veins and capillaries), some invertebrate groups have an open circulatory system containing a heart but limited blood vessels.

Explanation:

Humans have closed circulatory systems. This means that blood is always enclosed in vessels and the heart while circulating throughout the body.

of those who start drinking before they're 15 will develop alcohol dependence

layer 3 is younger than layer 6.