For the function $f$ whose graph is given above in the rectangular coordinate plane
$$\begin{aligned}
& \int_{a}^{c} |f(x)|\, dx = 20 \\
& \int_{a}^{c} f(x)\, dx = 8
\end{aligned}$$
the equalities are satisfied.
What is the value of
$$\int_{a/2}^{b/2} f(2x)\, dx$$
?
A) $-3$
B) $-4$
C) $-5$
D) $-6$
E) $-7$