1) holds the solar system together by attracting all planets to orbit the central sun?
a) gravity
b) tides
c) eclipse
d) moon phases

what do scientists believe the moon’s core might be formed of?
a) iron
b) silicon
c) carbon
d) lava

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.