what options does a illegal teenager have to become a citizen, when both the parents are also immigrants?

There are various issues as to what they might qualify for. However, if they are under 21, they can climb on the petitions of their parents. Thus, we would have to see what the parents might qualify for. If the child is under 18 years and 6 months, they should consider leaving the U.S. because they would not be subject to the 3/10 year bar.