3. Arrange the sequence of numbers $\sqrt{2}, 2, \sqrt{6}, 2 \sqrt{2}, \sqrt{10}, \cdots$, $2 \sqrt{51}$ as follows:
\begin{tabular}{cccccc}
$\sqrt{2}$ & 2 & $\sqrt{6}$ & $2 \sqrt{2}$ & $\sqrt{10}$ & $2 \sqrt{3}$ \\
$\sqrt{14}$ & 4 & $3 \sqrt{2}$ & $2 \sqrt{5}$ & $\sqrt{22}$ & $2 \sqrt{6}$ \\
$\sqrt{26}$ & $2 \sqrt{7}$ & $\cdots$ & $\cdots$ & $\cdots$ & $\cdots$ \\
$\vdots$ & $\vdots$ & $\vdots$ & $\vdots$ & $\vdots$ & $\vdots$ \\
$\cdots$ & $\cdots$ & $\cdots$ & $\cdots$ & $\cdots$ & $2 \sqrt{51}$
\end{tabular}

If the position of $3 \sqrt{2}$ is denoted as $(2,3)$, and the position of $2 \sqrt{7}$ is denoted as $(3,2)$, then the position of the largest rational number $n$ in this sequence is denoted as (.
(A) $(20,3)$
(B) $(3,20)$
(C) $(2,17)$
(D) $(17,2)$
3. D.

Observing this sequence of numbers, we can see that it represents the arithmetic square roots of positive even numbers, and the last number's radicand is 204. To find the position of the largest rational number in this sequence, we need to identify the largest perfect square less than 204 among the radicands, which is 196. According to the pattern of the sequence, 196 is in the 98th position, so the largest rational number in this sequence is in the 17th row, 2nd column.