Find the Values of the Variables for Which the Statement

Multiple Choice

Find the values of the variables for which the statement is true, if possible.
- $\left[ \begin{array} { l l l } 4 & \mathrm {~b} & 2 \end{array} \right] + \left[ \begin{array} { l l l } \mathrm { a } & 9 & \mathrm { c } \end{array} \right] = \left[ \begin{array} { l l l } 2 & 3 & - 7 \end{array} \right]$

A) $a = 6 ; b = 12 ; c = - 5$
B) $a = \frac { 1 } { 2 } ; b = \frac { 1 } { 3 } ; c = - \frac { 7 } { 2 }$
C) $a = 2 ; b = 6 ; c = 9$
D) $a = - 2 ; b = - 6 ; c = - 9$