1) A challenge you faced when you first came to the US and how you overcame that challenge. (Example: You can face your fears and overcome obstacles.)
2) A conflict you have had on a team or relationships(a roommate, for example) and how you deal with it. (Example: You worked on a team with people who were not committed to the project, and it's important to learn to communicate and build relationships to accomplish the work)
3) A challenge you faced when making a decision on your major or career path(maybe a different opinion from your parents, for example, or low scores on a subject that you needed to succeed in your major). (Example: It is important to follow your heart instead of only doing what others think is best for you. or past difficulties don't determine your future.)