Correct Answer - C
`sqrt(20)+sqrt(12)+root(3)(729)-4/(sqrt(5)-sqrt(3))-sqrt(81)`
`implies2sqrt(5)+2sqrt(3)+9`
`-(4/(sqrt(5)-sqrt(3)))xx(sqrt(5)+sqrt(3))/(sqrt(5)+sqrt(3))-9`
`implies 2sqrt(5)+2sqrt(3)+9-((4(sqrt(5)+sqrt(3)))/2)-9`
`implies2sqrt(5)+2sqrt(3)+9-2sqrt(5)-2sqrt(3)-9`
`implies0`