premise: A zoo's reptile house has a straight row of exactly five consecutive habitats—numbered 1 through 5 from left to right—for housing exactly seven reptiles—four snakes and three lizards. Five of the reptiles are female and two are male. The reptiles must be housed as follows: No habitat houses more than two reptiles. No habitat houses both a snake and a lizard. No female snake is housed in a habitat that is immediately next to a habitat housing a male lizard. Which one of the following must be true?
hypothesis: At least one male reptile is alone in a habitat.