$\overrightarrow{a}, \overrightarrow{b}, \overrightarrow{c} $ are three vectors, such that $\overrightarrow{a} + \overrightarrow{b} + \overrightarrow{c} = \overrightarrow{0}, \; |\overrightarrow{a}| = 1, \; |\overrightarrow{b} |= 2, \; |\overrightarrow{c} | = 3$, then $\overrightarrow{a}. \overrightarrow{b} + \overrightarrow{b}.\overrightarrow{c} + \overrightarrow{c}.\overrightarrow{a}$ is equal to :

Question

( A ) $7$
( B ) $0$
( C ) $-7$
( D ) $1$