Below You Are Given a Partial Computer Output from a Multiple

Below you are given a partial computer output from a multiple regression analysis based on a sample of 16 observations. $$\begin{array}{l}\begin{array} { l l } \text { Coefficients } & \text { Standard Error } \\12.924 & 4.425 \\- 3.682 & 2.630 \\45.216 & 12.560\end{array}\\\text { Analysis of Variance }\\\begin{array} { l l l l l } \text { Source of } & \text { Degrees of } & \text { Sum of } & \text { Mean } \\\text { Variation } & \text { Freedom } & \text { Squares } & \text { Square }\end{array} \quad F\end{array}$$
The degrees of freedom for the sum of squares explained by the regression (SSR) are

A) 2.
B) 3.
C) 13.
D) 15.