Which best describes the pericardium? structures inside the heart that ensure that blood flows in one direction only
a sac around the heart that allows the heart muscle to receive oxygen
a sac around the heart that protects the heart and chest tissues
structures inside the heart that bring blood to the lungs for oxygenation

c

Explanation:

The pericardium is a thin sac that surrounds your heart. It protects and lubricates your heart and keeps it in place within your chest

The answer is C on edge, a sac around the heart that protects the heart and chest tissue.

Explanation:

I just did the test

the circled areas are referred to   as sunspots.   the sunspots are cooler than the   surrounding area.

sunspots are temporary phenomena on the photosphere of the sun that appear visibly as dark spots compared to surrounding regions. they correspond to concentrations of magnetic field flux that inhibit convection and result in reduced surface temperature compared to the surrounding photosphere.

is it multiple choice?