1. **Which of the causes of periodic shortness of breath is less prominent?**
**A. Myocardial ischemia** - Myocardial ischemia typically presents with more consistent symptoms of shortness of breath rather than periodic episodes. On the other hand, asthma, pulmonary embolism, and COPD are commonly associated with periodic shortness of breath.
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2. **In the cause of platypnea, which diagnosis is more common?**
**C. Hepatopulmonary syndrome**