The patient is suffering from cardiac tamponade, that is, filling of the pericardial cavity with fluid. The classic signs of this tamponade are referred to as "Beck's triad." This trio, by definition, includes a small heart, from compression of the heart by the fluid-filled pericardial sac, and a quiet heart because the tamponade muffles the cardiac sounds; decreased pulse pressure resulting from the reduced difference between systolic and diastolic pressure because the tamponade restricts the ability of the heart to fill in diastole; and increased central venous pressure because venous blood cannot enter the compressed heart. None of the other answers provided includes these data to fit the definition.