If $f(x) = \begin{cases} 3x - 2, & 0 < x \leq 1 \\ 2x^2 + ax, & 1 < x < 2 \end{cases}$ is continuous for $x \in (0, 2)$, then $a$ is equal to: (A) $-4$ (B) $-\frac{7}{2}$ (C) $-2$ (D) $-1$