2. A sample is $1,3,2,2, a, b, c$. It is known that the mode of this sample is 3, and the mean is 2. Then, the variance of this sample is ( ).
(A) 8
(B) 4
(C) $\frac{8}{7}$
(D) $\frac{4}{7}$
2.C.

Given the sample mean is 2, we have
$$
1+3+2+2+a+b+c=2 \times 7=14 \text {, }
$$

Thus, $a+b+c=6$.
Since the sample mode is 3, it means that at least two of $a, b, c$ are 3, and the other one is 0. Therefore, the sample variance is
$$
s^{2}=\frac{1}{7}(1+1+0+0+1+1+4)=\frac{8}{7} .
$$