Here's how to correct it and what it means:
Correct options:
* ¿Qué prefiere mi amigo? - This translates to "What does my friend prefer?" This is a question asking about your friend's preference.
* Mi amigo prefiere... - This translates to "My friend prefers..." This is a statement indicating your friend's preference. You would need to complete the sentence with the specific thing your friend prefers.
For example:
* Mi amigo prefiere la pizza. - My friend prefers pizza.
Let me know if you have any other Spanish phrases you'd like help with!