Why are no rocks found that date from the first 800 million years of Earth's
existence?
A. All the rocks from that time period have been destroyed by plate
movements.
B. They have all been buried too deeply under newer rocks.
O C. Earth was too hot to have solid rocks at that time.
D. They were all destroyed by a comet impact.

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.