 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. He touched buttons by the edge of the bed and the illumination quieted to a soft glow, wrapping her in a radiant halo. New York lay quietly below him. It was the hour of indecision when day has not quite made up its mind to leave and night has not yet attacked in force. 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. Within six months, half of the world's population was gone. Less than a month ago no more than a few thousand people remained in New York. 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. On these screens could be graphed the population of any and every part of the globe. An illuminated counter immediately above it would give the numerical strength of the area being sampled while the screen would show population density by individual pinpoints of light that merged to form brightness patterns. Charles activated the switches that would flash a schematic map of New York on the screen. "There's bound to be somebody else left here. "Why, it was just yesterday (or was it the day before?) that ten of us, at least, met here to check the figures. Charles was by himself, the last person alive in all of New York City.
 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