If the question is, why is this study faulty? Then you can answer it. We know nothing about what was asked. (How could it be much more than "Where do you live?" The last one is wrong.
Is there missing data? We don't know. So the second last one is not the best answer.
The sample is too small. So far that's your best answer.
The results cannot be at fault. How can saying 2/3 of the people answered that they lived in the country.
