What is a main difference between Mercury and Neptune? Mercury is an inner planet with a thicker atmosphere and a longer year than Neptune.
Mercury is an inner planet with a thinner atmosphere and a shorter year than Neptune.
Neptune is an inner planet with a thicker atmosphere and a shorter year than Mercury.
Neptune is an outer planet with a thinner atmosphere and a shorter year than Mercury.

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.