n - m(1-(m-1)/m)^n)
For a slot collision doesn't occur given by following probability ..
1-((m-1)/m)^n
Expectation for m slot collision doesn't occur...
m((1-((m-1)/m)^n -------------- equation A
So for n keys expected number of times collision occur is ...
n - equation A
Take n= 32 and m=32 it will gives 11.58
So ans should be D.