Read the sentence and answer the question. they ate lunch in the restaurant and then they took their dog for a walk in the park. which correctly shows where a comma is needed in the sentence?

a. they ate lunch in the restaurant, and then they took their dog for a walk in the park.

b. they ate lunch in the restaurant and then they took their dog, for a walk in the park.

c. they ate lunch in the restaurant and then they took their dog for a walk, in the park.

d. they ate lunch in the restaurant and, then they took their dog for a walk in the park.