question:  What is the true explanation for Charles being the last man on Earth?
context: There should be an epitaph for every man, big or little, but a really grand and special one for Loner Charlie. [Transcriber's Note: This etext was produced from Planet Stories Fall 1954. New York lay quietly below him. To any man, WHO HAPPENED TO BE THE LAST MAN ON EARTH! Buildings were taller, men were healthier, most of the problems of humanity seemed licked, or nearly so. 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. Then just one year ago, the first human became infected with the strange malady. 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. Housed as it was in a huge metallic globe of a building, it contained computers which kept exact account of every human on earth. 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. 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.
output:  The invisible aliens exterminated people in alphabetical order, according to the the Bureau of Vital Statistics index. Charles happens to be last on the list, with the last name Zzyzst.
options:  The invisible aliens exterminated people according to chance and probability. Charles just so happened to be killed last.  The invisible aliens exterminated people in alphabetical order, according to the the Bureau of Vital Statistics index. Charles happens to be last on the list, with the last name Zzyzst.  The invisible aliens exterminated people according to how normal they were. Charles just so happened to be the most normal human alive.  The invisible aliens exterminated people in the order of a foretold prophecy. Because he was a prophet, Charles was killed last.