Learn Farsi: این شرکت‌کننده کدام نامزد را انتخاب می‌کند؟ - Which candidate does this participant choose?

It uses the agent noun pattern you are currently learning! شرکت means participation and کن is the present stem of کردن (to do). Adding the suffix نده makes it a person who does the action. So, شرکت‌کننده literally means participation-doer or participant.

Why is را used after کدام نامزد?

The word را marks the specific direct object of a sentence. Because the question asks about a specific selection (which candidate), the candidate being chosen is definite. Therefore, نامزد needs را right after it to show it receives the action of the verb.

I learned before that نامزد means fiancé. Does it also mean candidate?

Yes! While نامزد means fiancé or fiancée in a romantic context, it is also the standard Farsi word for a candidate or nominee in an election, a job application, or a competition.

Why does the question word کدام come in the middle of the sentence instead of at the beginning?

In Farsi, question words usually sit in the exact same place in the sentence as the answer would. Since the candidate is the object of the sentence, کدام نامزد goes in the normal object position, right before the verb. The subject این شرکت‌کننده stays at the beginning.