This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Orthopaedics
A patient developed breathlessness and chest pain, on second postoperative day after a total hip replacement. Echo-cardiography showed right ventricular dilatation and tricuspid regurgitation.What is the most likely diagnosis - 
Select and explain. 
A. Acute MI, B. Pulmonary embolism, C. Hypotensive shock, D. Cardiac tamponate
B: Pulmonary embolism
Answer: B: Pulmonary embolism 
Explanation: Onset of chest pain and breathlessness, together with echocardiographic evidence of right ventricular dilatation and tricuspid regurgitation after a high risk procedure (for thromboembolism) like total hip replacement suggests a diagnosis of pulmonary embolism.