Which best explains the circulation system within mammals?
a. mammals use a closed, single-loop circulatory system aided by a four-chambered heart.
b. mammals use a closed, double-loop circulatory system aided by a four-chambered heart.
c. mammals use an open, double-loop circulatory system aided by a four-chambered heart.
d. mammals use a closed, single-loop circulatory system aided by a three-chambered heart.

Answer is: B. Mammals use a closed, double-loop circulatory system aided by a four-chambered heart.

In closed circulatory systems blood never leaves the blood vessels.

Closed circulatory systems are divided into single circulatory systems and double circulatory systems.

Birds and mammals have double circulation (pulmonary and systemic) and this circulatory system have a four chambered heart.

The right atrium receives deoxygenated blood and the right ventricle sends it to the lungs to be oxygenated; the left atrium receives oxygenated blood from the lungs and the left ventricle sends it to the body.

whats the meaning of /

your answers are a,b,,e and f

i hope this