All of the following may be seen in patients of cardiac tamponade, except:
Kussmaul's sign is an increase rather than the normal decrease in CVP during inspiration, is most often caused by severe right-sided hea failure; it is a frequent finding in patients with constrictive pericarditis or right ventricular infarction. Kussmaul's sign is present in constrictive pericarditis and its is a clinical sign differentiating cardiac tamponade from constrictive pericarditis. Kussmaul's sign is a rare in cardiac tamponade. All other features mentioned above are associated with cardiac tamponade. So "Kussmaul's sign" is the single best answer of choice. Ref: Harrisons Principles of Internal Medicine, 16th Edition, Pages 1415-17.
Kussmaul's sign
Pulsus paradoxus
Electrical alternans
Right ventricular diastolic collapse on echocardiogram