2 What do the arrows on the graph below represent?
-4,000
-3,000
-2,000
1,000
(singular Genus)
Number of Genera
0
500
100
400
300 200
Millions of Years Ago (mya)
A. extinction events
B. meteorite impacts
C. changes in Earth's temperature
D. the evolution of a new species

How is it possible for someone to put an ear to a wall and hear someone in the next room?     a.sound waves can travel though solids.    b.the waves travel from room to room via air.    c.there must be some air in the wall so the sound can travel through it.    d.sound waves change to electromagnetic waves and then back again.