Answer
Choice B
Work Step by Step
The given expression, $
\sqrt[]{30}
,$ is closest to $5$ since $5^2=25.$
The given expression, $
\sqrt[]{10}
,$ is closest to $3$ since $3^2=9.$
The given expression, $
\sqrt[]{90}
,$ is closest to $10$ since $10^2=100.$
Hence, the perimeter of the given triangle, $
\sqrt{30}+\sqrt{10}+\sqrt{90}
,$ is closest to
\begin{array}{l}\require{cancel}
5+3+10
\\\\=
18
.\end{array}
Hence, $\text{
Choice B
.}$
