Answer:
Asking people at an international airport can be thought of as bias because there might a lot of people at the airport who are old and who like to travel.
Asking people whether they’d prefer Italy or France could be bias because what if the people are Italian? Then they’d obviously choose Italy. Or maybe they’re French and they’ve lived in France and been to France too many times and they’d rather visit Italy.
If 86% of people asked took a French course, you can assume they want to learn French (obviously) and that they probably want to learn French so they can visit and be able to communicate with others in France.
Explanation: