Answer:
All three sentences are in French and ask about whether or not someone ate a sandwich, but there are differences in their structure and level of formality.
1. "Mangé-elle un sandwich?" is an inversion question, where the subject and verb are inverted. It is more formal and is often used in written French. The correct form would be "A-t-elle mangé un sandwich?" in spoken French.
2. "Est-ce que elle est mangé un sandwich?" is not correct grammatically. The correct form would be "Est-ce qu'elle a mangé un sandwich?" This is a more informal question that uses the phrase "est-ce que" to form a question.
3. "A-t-elle mangé un sandwich?" is also a formal question, but it uses the inversion structure rather than "est-ce que". It is equivalent in meaning to "Mangé-elle un sandwich?"
Step-by-step explanation: