 What are the four hypotheses Charles has about how he might have survived the plague?
There should be an epitaph for every man, big or little, but a really grand and special one for Loner Charlie. New York lay quietly below him. The largest cotton crop ever was forecast and rumors from Mexico had it that no one had died from scorpion bite in several weeks. A month later the meat animals, the birds and the household pets began dropping as rapidly as the flies which had dropped earlier. Within a year it was obvious to everyone that man was the only animal left on earth. The panic which had begun with the death of the animals was quieted somewhat by the fact that humans seemed immune to the pandemic. But the lakes full of dead fish caused a great stink and residents along the coasts began to move inland. And now.... "I've got to find out," Charles told himself. Before the plague the Bureau of Vital Statistics had been one of man's crowning achievements. Once a year the Bureau issued The Index, an exact accounting of Earth's four billion inhabitants. Only once, before the plague, had he seen the interior of this room. All children had to have a brain-wave recording made by the Bureau during the first month of their life. And again at the age of 10 each child returned to the Bureau for a recheck. It was for this latter recording that Charles had come to the Bureau some twenty-two years before and a friendly guard had let him peep briefly into the computer room.
 He’s too normal to get it; pure chance; he’s a saint; immunity
 He’s too strange; he’s a prophet; the odds were against him; he got a vaccine  He’s a nice guy; pure chance; he’s a prophet; he received medical treatment.  He’s healthier than everybody; pure chance; he knows a good doctor; he wore a mask  He’s too normal to get it; pure chance; he’s a saint; immunity