Development in interest in nursing.
What is meant by this? I think you might mean "the development of my interest in nursing."
This could include discussion of nursing philosophy (i.e. altruism, human dignity, etc.), so you could actually choose the first topic but also write about concepts from the second topic.
I think that the best thing to do is choose this topic about the development of your interest in nursing and write about what makes you want to choose this instead of some other program. What makes you want to learn nursing instead of continuing with dentistry?
Most importantly, come up with a theme that will help the reader to remember you. Make sure you use a memorable phrase or word, and you can use it in the beginning, middle, and end of the essay.
When you have written something, we'll help you correct any errors you might have.