If you are truly qualified for the job then you should be ready to build your case. To do this you will need to demonstrate that your educational and work background has developed abilities and skills that meet the needs of the job. You can provide specific examples from your background that appear on your CV or resume. This proves you have researched the job and carefully considered how the job matches your credentials.
This is a tough question because it clinch the job for you or lose it. Basically what the interviewer is looking for is an honest answer as to why you would be best, I.e. you are a quick learner, you have not only the educational background but real world experience as well and things like that. The most important thing to remember is not to be cocky, that will lose you the job every single time.
The answers here are pretty good but I will add you should look your best when you go for your interview.Not too much make up gals, or too strong cologne guys..First impressions count. Answer questions directly and look into the interviewer's eyes. You are best qualified because? You enjoy working with the public/traveling/the type work involved/ whatever the job requires.. Remark also that you enjoy learning new concepts etc. talents and you feel you can accomplish this at so and so's place of business. Mentioned that you feel you can learn the business to satisfy the company and that you wish to be an asset and feel that you can be an asset.Good luck :)
You can give precise instances from your background that are present on your CV or resume. This will prove you have studied the job and with awareness, considered how the post matches your qualifications. You are advised to talk about the activities, relations, and exact skills that make you eligible for the job.