旅行の前に、ホテルを予約し___。
Q. Which ending expresses 'book in advance (as preparation)'?
Translation
I'll book the hotel before the trip (in preparation).
Explanation
〜ておく means doing something in advance for future convenience: 予約しておきます. 〜てしまう stresses completion/regret and 〜てみる means 'try doing'.