Meg constructed triangle POQ and then used a compass and straightedge to accurately construct line segment OS, as shown in the figure below:

As you can notice on the given image, segment OS bisects angle POQ. It means that angle POQ is twice the angle POS.
Then, you can conlude, due to the given answer choices, than the measures of angles POS and POQ are:
m∠POS = 20
m∠POQ = 40