A scientist maintains a healthy culture of a single species of bacteria in a container. She then introduces a new substance into the bacterial culture. Within a day, most of the bacteria died.
Which of the following best explains why some of the bacteria survived?
a
They mutated and became a different species after exposure to the substance.
b
They had a genetic variation that gave them resistance to the added substance.
c
They absorbed the substance and broke it down in their digestive systems.
d
They were exposed to the substance long enough to develop a resistance to it.
b
They had a genetic variation that gave them resistance to the added substance.