The thing is that every 4 years, the tree grows 6 inches, so that could be expressed as a ratio, 4/6. That also means that every two years, the tree grows 3 inches since it could be simplified to 2/3.
√52-√13+√117
sqrt (4*13) - sqrt (13) + sqrt (13*9)
sqrt(4)sqrt(13) -sqrt(13)+sqrt(13)sqrt(9)
2sqrt(13) -sqrt(13)+3sqt(13)
sqrt(13)[2-1+3]
4sqrt(13)
Choice A