【单选题】
设一元线性回归模型:<img src="https://nimg.ppkao.com/2019-04/wuacheng/2019041217042123472.jpg?sign=cce06c1e2c3562a2e6aef453b56f16e9&t=62d74368" />且ε<sub>i</sub>各相互独立.依据样本<img src="https://nimg.ppkao.com/2019-04/wuacheng/2019041217043923522.jpg?sign=d80292b120e5e7d9d72bd403b40f0567&t=62d74368" />得到一元线性回归方程<img src="https://nimg.ppkao.com/2019-04/wuacheng/2019041217044973884.jpg?sign=a53f27c088c91d97ad3215337a56d3e7&t=62d74368" />,由此得x<sub>i</sub>对应的回归值为<img src="https://nimg.ppkao.com/2019-04/wuacheng/2019041217045892265.jpg?sign=bdfc2911dd135f1fea1d18016123f992&t=62d74368" />的平均值<img src="https://nimg.ppkao.com/2019-04/wuacheng/2019041217051777112.jpg?sign=ece915a7cc2fc543ba25472bf8abb9d5&t=62d74368" />,则回归平方和S<sub>回</sub>为()<br /> <img src="https://nimg.ppkao.com/2019-04/wuacheng/2019041217235992368.jpg?sign=678460b1ad80e80927a32944f3b1cfe8&t=62d74368" />
A、A
B、B
C、C
D、D