Answer:
Quasi-experimental design.
Explanation:
The study described uses two groups, one of them will have glasses and the other group won't. In other words, one group will have the estimulus and the other one won't.
The group that has sunglasses is called experimental group.
The group that doesn't have sunglasses is called control group.
Basically, this methodology consist in having two difference groups, where one of them has the treatment or stimulus and the other doesn't. Then, after the experiment, variables will be measured to compare and deduct if the hypothesis is true or not.
This is called a quasi-experimental design.