Which of the following is an example of an adaptation?
 A.Birds that live near a highway learn not to fly away every time a car passes. 
B.The coloring of a monarch butterfly alerts predators to the fact that the butterfly is poisonous. 
C.A dog sits when it hears a command because the owner rewards it with food. 
D.Pigeons make their nests near an outdoor restaurant, where food is always available.