Why doesn't the premise in the stimulus that recovery rates at the two hospitals are similar for similar diseases rule out answer C? Answer C, which says that the hospitals tend to treat different illnesses, seems to contradict this premise. I chose answer D because if there are patients with the sa...

I am also not seeing how E is a better choice than C. Physical labor is not necessarily the same thing as physical exercise and we don't know that the people who sit at desks aren't exercising.