The correct option is C 4n+2
There is one square number between n2 and (n+2)2 which is (n+1)2.
There are 2n non-square numbers between n2 and (n+1)2, and 2(n+1) non square numbers between (n+1)2 and (n+2)2.
Hence, in total, there are 2n+2(n+1)=4n+2 non square numbers in between n2 and (n+2)2.