Correct answers !

the modern domesticated dog is thought to be descended from the wild wolf. there are currently many breeds of domesticated dogs which vary greatly in appearance.

which of the following best describes how the modern day dog has changed from its ancestor, the wolf?

a. humans have cloned dogs for desirable traits, causing many differences among breeds.

b. humans have bred dogs for desirable traits, causing many differences among breeds.

c. the modern dog gradually changed over time due to natural selection.

d. the modern dog quickly changed due to extinction.

B. Humans have bred dogs for desirable traits, causing many differences among breeds.

Explanation:

The evolution of modern day dog from its ancestor has been driven mainly by artificial selection for desirable traits by humans.

Artificial selection has to with deliberate act of selectively breeding organisms based of some desirable traits so as to get a desirable hybrid. This is opposed to natural selection in which natural forces selects for which organism breeds with which.

Up till today, most modern day dogs are still being manipulated for selective breeding in order to achieve more sophisticated breeds of dogs. This has led to the existence of wide variety of dog breeds which are different from their wolf ancestor.

The correct option is B.