There is no question that raising teenagers is a challenge no matter how many parents are living in the home. Particularly challenging are the ages between 12 and 16,which are marked by mood swings, defiant attitudes, and attempts to push the limits set by their parents. During this time, teens are trying their hardest to gain adult independence, which is a normal part of the natural growing process. So, we accept this as a time to help them learn lessons and find their way to adulthood, despite the fact that it sometimes makes us feel like we are raising aliens from another planet! Two parents in the household can be a definite plus during these years, especially if both are healthy and loving. In single parent homes, a healthy and loving atmosphere is also a key ingredient to raising responsible teens. Also, teens are often masters at pitting (使人相斗)their parents against one another, so when they have divorced parents living in different households, it can be extra difficult to co-parent with effectiveness. What can single parents do to make the teens in their homes more pleasant The suggestion is to create realistic and enforceable boundaries. Let your kids know that you will negotiate boundaries every six months, for instance. Let them come up with ideas so that they will be more apt to comply. The topics to discuss may be such as how they spend their time after school, how they spend time with their friends and how should be their dress code and their hairstyles, and so on. However, when it comes to alcohol, drugs, smoking and other obvious health risks, there should be no negotiation at all. I never give them permission to drink—and that was final. Let them know they are responsible for their own behavior and should take themselves out of situations that could lead to trouble. A week before your six-month meeting with your teen, call the other parent and talk about how things have been going in each household. Most of the time, there is a wide range of healthy variations in parenting styles. Explain to your teens that when they enter the workforce, they will work with different supervisors, so operating under different household guidelines should be respected and will be good training for their future. What is the main idea of the passage

A. To teach the single parent how to raise teens successfully.
B. To show how difficult it is to raise teens.
C. To show to the children that following different rules in different homes is helpful for their future work.
D. To show the single parent that he or she should make friends with the other parent.