Read the following sentences from the article.

1. In fact, the brain is not fully developed and protected until people are in their mid-twenties.

2. During the teen years, new synapses make the adolescent brain a learning machine, better at absorbing facts, ideas, and skills.

3. Adolescence is a perfect time in a person's life to gain new skills and practice them, but adults have to remember that the teen brain is not fully developed, and it changes from day to day.

4. Developing executive functioning skills typically begins in childhood through learning how to complete goals, and through adolescence, teens learn how to plan and organize more complicated goals.

Which two sentences taken together provide the BEST evidence to support the idea that the brain keeps growing after the teen years?