What the author does to strengthen his or her argument is D. He or she addresses and refutes an opposing viewpoint.
The message that the author is trying to convey is that no matter how hard or unimportant it may seem, parents should not give up trying to make the right choices. To do so, he or she deals with the consequences of both trying to make the right decision and falling into the temptation of not doing so. Therefore, he is refuting and opposing viewpoint to strengthen his or her argument.