Let ${\bf u}$ be a vector and $c_1$ and $c_2$ be scalars.

Select the best statement.

A. $c_1 + ({\bf u})c_2$ is not defined.
B. $c_1 + ({\bf u})c_2 = c_1+c_2{\bf u}$
C. $c_1 + ({\bf u})c_2 = c_1c_2+{\bf u}$.
D. $c_1 + ({\bf u})c_2 = c_1c_2+c_2{\bf u}$
E. none of the above