A response variable you are trying to measure once you've done the experiment.
What have you done? You've measured what sunglasses will do to affect eyesight. You have used a 10 week period to measure their response. You don't really care what the response is -- only if there is one.
10 people and 10 weeks don't change. Those two are not a choice for an answer. Now you come to the crunch of the question. Is it the sunglasses you are trying to measure or is it what your eyes have done because you were wearing sun glasses.
So we need an answer. If you say sun glasses, how did you measure what they did. THAT's the answer. The answer is not the sunglasses.
