What is type of fluid is found in the pericardial cavity? What is the purpose of this fluid?

The Heart

A = the outer serous membrane pericardium.
B = the pericardial cavity
C = the also known as the visceral pericardium.
What is type of fluid is found in the pericardial cavity?
What is the purpose of this fluid?

ETC.Complete Attached Worksheet. Assignment Will Be Located In "Files"