Correct Answer - A
`1/(sqrt(2)+1)+1/(sqrt(3)+sqrt(2))+1/(sqrt(4)+sqrt(3))+1/(sqrt(5)+sqrt(4))+`
`1/(sqrt(6)+sqrt(5))+1/(sqrt(7)+sqrt(6))+1/(sqrt(8)+sqrt(7))+1/(sqrt(9)+sqrt(8))`
After Rationalizing
`=(2sqrt(2)-1)+(sqrt(3)-sqrt(2))+(sqrt(4)-sqrt(3))+(sqrt(5)-sqrt(4))`
`+(sqrt(6)-sqrt(5))+(sqrt(7)-sqrt(6))+(sqrt(8)-sqrt(7))+(sqrt(9)-sqrt(8))`
`=sqrt(9)-1=3-1`
`=2`