Question

what is the main reason jilly researched the consequences of teens not getting enough sleep? to learn about scientists who study teens sleep habits to encourage young people to go to bed earlier to show the board why its better to start school later to understand the effects of her own internal clock

Explanation:

Researching the consequences of teens not getting enough sleep is likely related to advocating for a change (starting school later) to address the issue. The other options are either too narrow (learning about scientists, understanding her own clock) or not the main - focus (encouraging to bed early is a possible outcome but not the main reason for research in a school - board context).

Answer:

to show the board why it's better to start school later