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: Pediatrics
Pure left sided failure may be seen with –a) ASDb) Aortic stenosisc) Patent ductus arteriosusd) Pulmonary valvular obstruction 
Select and explain. 
A. a, B. c, C. bc, D. ad
C: bc
Answer: C: bc 
Explanation: ASD usually does not cause HF.
AS & PDA increase the strain on left ventricle -> LVF.
PS increases the strain on right ventricular failure ---> RVF.