If $|\overrightarrow a|=2,\:|\overrightarrow b|=3\:and\:|\overrightarrow c|=4$ and $\overrightarrow a+\overrightarrow b+\overrightarrow c=\overrightarrow O$, then $\overrightarrow b.\overrightarrow c+\overrightarrow c.\overrightarrow a+\overrightarrow a.\overrightarrow b=?$

Question

$\begin{array}{1 1} \large\frac{19}{2} \\ \large\frac{-19}{2} \\ \large\frac{29}{2} \\ \large\frac{-29}{2}\end{array}$