Step 1: Approach this as a bundle diagnosis. Pediatric ARDS needs several boxes ticked at once, so a single option is unlikely to be the whole answer. Step 2: Box 1 is timing: the picture must develop within 7 days of a recognised insult. Step 3: Box 2 is origin: the hypoxaemic respiratory failure must not be fully explained by cardiac failure, fluid overload, or left ventricular dysfunction. Both option b and option c describe this exclusion of a cardiac cause. Step 4: Since the definition simultaneously requires the timing AND the exclusion of cardiac causes, every listed statement is correct, so the answer is all of the above. \[\boxed{\text{All of the above}}\]