Advice for initial phone interview?

I am currently at a job that I’ve been at for just over 3 months. My boss is a d*ck so I’m leaving. Tomorrow I have my first interview at a new place( for a clinical research coordinator). Im super nervous! It’s just with a recruiter but I want to do my best. What should I be prepared for ? I’m also thinking the may ask me why I’m leaving my company and why I had a 9 month gap in employment (took time off to study for MCAT and apply to med school). These are questions I feel I may have a tough time answering.

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