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: Pathology
Sudden death, right sided heart failure (cor pulmonale or cardiovascular collapse) occur when - 
Select and explain. 
A. Small pulmonary embolism, B. Massive pulmonary embolism, C. 60% or more of pulmonary artery is obstructed with emboli, D. End artery obliteration
C: 60% or more of pulmonary artery is obstructed with emboli
Answer: C: 60% or more of pulmonary artery is obstructed with emboli 
Explanation: None