Looking at the coordinate plane, Trapezoid A is above the $x$-axis and Trapezoid B is below the $x$-axis and shifted to the left.

To map A onto B:

1. Reflect over the $x$-axis: This flips Trapezoid A to below the $x$-axis (same $x$-coordinates, negated $y$-coordinates).
2. Translate to the left: This shifts the reflected trapezoid to align with Trapezoid B.

The correct transformation is a reflection over the $x$-axis followed by a translation to the left.