Use this opportunity to reiterate your strengths, tailored to fit the job requirements. Your 3 reasons can include a combination of your technical skills, soft skills, past accomplishments, awards and recognition, and previous experience. A sample answer would be, "I believe that I am the best for this position because of my extensive customer service experience and my ability to adapt to any situation. I always go the extra mile and am highly dedicated to my work. In all that I do I would strive to advance the company and I feel that my previous work experience proves that."