Why does all mammals have seven vertebrae (bones) in their neck? A) all mammals descended from a common ancestor
B) predators only eat animals with six neck vertebrae
C) all animals can turn their heads the same amount
D) all mammals have to stretch their necks to obtain food

Based on the observation that only male crickets produce a song, you hypothesize that a male's song is a form of communication to potential mates. you set up a simple experiment to test this hypothesis. in the laboratory, you place a male snowy tree cricket in enclosure a, which is adjacent to enclosureb. in enclosure b, you place other insects, one at a time, and observe their responses to the male's song. the enclosures are designed so that the two insects being tested cannot see or smell each other, but sound is transmitted from enclosure a to enclosureb.