Interesting Chest Xray

Spot diagnosis:
a. Something's definitely abnormal but dunno where.
b. He might have swallowed a ball.
c. Why-heart-so-big-one syndrome
d. None of the above=p

This is a 10 year-old boy presented with chest pain, associated with worsening severe breathlessness for 2 days, with history of URTI symptoms about 2 weeks ago. He was in respiratory distress and was nearly intubated. ECHO showed