2. The set of positive even numbers $\{2,4, \cdots\}$ is divided into groups in ascending order, with the $n$-th group containing $2 n-1$ numbers:
$$
\{2\},\{4,6,8\},\{10,12,14,16,18\}, \cdots \cdots .
$$

Question: In which group is 2010 located?
(A) 30
(B) 31
(C) 32
(D) 33
2. C.

Obviously, 2010 is the 1005th term of the sequence $a_{n}=2 n$. Suppose 2010 is in the $n$-th group. Then
$$
\begin{array}{l}
\sum_{i=1}^{n-1}(2 i-1)<1005 \leqslant \sum_{i=1}^{n}(2 i-1) \\
\Rightarrow(n-1)^{2}<1005 \leqslant n^{2} \\
\Rightarrow n=32 .
\end{array}
$$

Therefore, 2010 is in the 32nd group.