You could name any academic, organizational, professional, or relational strength that highlights who you are and what you're good at and is directly related to the nursing profession. All interview questions should be answered in a way that optimizes your chance to secure the position, so choose a strength that mirrors the values in the organization's mission statement or the work environment. While it may be true that you are efficient and organized and write amazing poetry, focusing on the former is a better match for an interview as an emergency room nurse.