The axis of symmetry of a parabola that has x-intercepts at \((-12, 0)\) and \((-6, 0)\) can be found by determining the midpoint of the x-intercepts.
To find the midpoint \(M\) of the x-intercepts, you can use the formula:
\[ M = \frac{x_1 + x_2}{2} \]
where \(x_1\) and \(x_2\) are the x-coordinates of the intercepts. In this case, \(x_1 = -12\) and \(x_2 = -6\).
Calculating the midpoint:
\[ M = \frac{-12 + (-6)}{2} = \frac{-18}{2} = -9 \]
Thus, the axis of symmetry of the parabola is \(x = -9\).
Therefore, the correct answer is:
x = -9