Answer:
C
Explanation:
To form unshaded trapezoid, you have to dilate the shaded trapezoid with the scale factor of 2 and the center of dilation at point (-5,1) and then translate the formed trapezoid 5 units to the right.
The translatin is the rigid tranformation that doesn't change the lengths of trapezoid's sides.
The dilation with scale factor 2 increases each length twice.
If the leg of trapezoid was 6 units long, then the length of the unshaded trapezoid's leg is 12 units.