The interviewer asks this question to hear what qualities you will bring to the agency and how you will benefit them if hired. Now is your chance to highlight your best characteristics and experience, showing the interviewer you have all the qualifications they require. If you review the job announcement before your interview, you will see the qualities, experience, and education the organization seeks in a dementia care specialist. Then, focus on using those keywords in your response. When describing how you meet their job requirements, the interviewer will see that you are a highly qualified candidate and place you high on the list.
As you were told, many qualified candidates are interviewing for the same position. You want to avoid speaking negatively of the other candidates or sounding arrogant when responding to this question. You want to sell yourself in the interview, but not while making the interviewer think you will be a challenging person to work with.