What is one reason that the surface water at the equator is less dense than the surface water at the poles?
A Water at the equator has faster-moving currents.
O
B. The equator receives less precipitation, making the water saltier.
C. The volume of water is much greater at the equator.
D. Water at the equator receives more sunlight, making it warmer.

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.