a) Show that Y/n is a maximum likelihood estimator of \(\displaystyle \lambda\)

b) Show that the estimator in part (a) is unbiased and consistent.

c) Also, show that Y/n is an efficient estimator of \(\displaystyle \lambda\)

I'm just confused on what I have to show for each part of the question. I know they each have their requirements for what you have to show for each, I just don't remember and I don't have my book with me to check.