A man with fever,dull-aching retrosternal chest pain reported to the emergency.On examination he was found to show pulsus paradoxus,Kussmaul's sign and increased jugular venous pressure.His apex beat was impalpable and heart sounds were muffled.Probable diagnosis is:

• A. Constrictive pericarditis
• B. Pericardial effusion
• C. Hemothorax
• D. Restrictive cardiomyopathy