The correct option is B 15 ml
The serous fluid which is secreted by the serous layer of the pericardium into the pericardial cavity is called as pericardial fluid. In human beings, 15 ml of pericardial fluid is released and reduces friction within the pericardium by lubricating the epicardial surface allowing the membranes to glide over each other with each heart beat. So, the correct answer is option B.