This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Medicine
A post operative cardiac surgery patient developed sudden hypotension, raised Central venous pressure, pulsus paradoxus at the 4th post operative hour .The most probable diagnosis is 
Select and explain. 
A. Excessive mediastinal bleeding, B. Ventricular dysfunction, C. Congestive cardiac failure, D. Cardiac tamponade
D: Cardiac tamponade
Answer: D: Cardiac tamponade 
Explanation: Ref Harrison 19 th ed pg 1573-1574 Features of rising pressure , falling aerial pressure and pulsus paradoxus following surgery on the hea leads us to the diagnosis of cardiac tamponade.