This type of interview question basically measures what the candidate looks for in a certain job and why he is opting for the given position. The best method to answer this question is to carefully think about your skillset and how you will improve and utilize them so as to prove that you are an asset to the company.

You can also add that you are motivated by your challenges and are constantly trying to improve yourself under any circumstance possible. This will give the interviewer the impression that you are an individual that always tries new challenges. This can also show the flexibility and adaptability that you have for the job.

You can also add certain other factors such as certain real life and recent problems or challenges that you had met and explain how you tried to overcome them.