Answer: b) frustrated
Explanation:
the word 'confused' would be the feeling of people who don't understand.
the word 'puzzled' would be the feeling of people who don't understand.
the word 'lost' would be the feeling of people who don't understand.
thus, the word 'frustrated' is correct, as it describes the emotion felt by the person who spoke French that people were confused, puzzled and lost because they could not understand what the person spoke.