question:  What is Evans' primary dilemma?
context: Like when there's no use trying—when it's time to give up because it's hopeless.... It was two days to sunrise, where Evans stood. The shadow line between day and night could be seen from the Moon to be drifting across Australia. Evans, who had no watch, thought of the time as a quarter after Australia. Evans was a prospector, and like all prospectors, a sort of jackknife geologist, selenologist, rather. Evans was about three hundred miles east of Williamson Town, the site of the first landing on the Moon. Evans was due back at Williamson Town at about sunset, that is, in about sixteen days. But his oxygen was too carefully measured; there was a four-day reserve. Four days reserve—plus one is five—plus sixteen days normal supply equals twenty-one days to live. This boiling lowered the temperature, and the condenser demonstrated its efficiency by quickly freezing the water in the tank. Evans sealed the turbine from the rest of the steam system by closing the shut-off valves. Or rather, he did have one illusion; he thought that he was completely unfit as a leader. For example, because of an order of his stating that there would be no alcoholic beverages within the survey building, the entire survey was assured of a constant supply of home-made, but passably good liquor. Morning to him had no meaning at all, but he thought in the strictest sense that it would be morning on the Moon for another week. The solar furnace was a rough parabola of mirrors used to focus the sun's heat on anything that it was desirable to heat. It was used mostly, from sun-up to sun-down, to supplement the nuclear power plant. Three of the nine banks of mirrors would not respond to the electric controls, and one bank moved so jerkily that it could not be focused, and it threatened to tear several of the mirrors loose. "That could hurt," Cowalczk admitted, "but there was only one of them."
output:  If he is to discover a new water source, he must utilize his low, existing source to find it
options:  He has a limited amount of time until the next meteor shower hits and permanently destroys his equipment  In submitting a claim to the lava mine, he will attract violence from those desperate for water  By entering into an unknown cave, he is possibly exposing himself to lava, which has the capacity to melt his space suit  If he is to discover a new water source, he must utilize his low, existing source to find it