‘- 중에(서)’ is placed after a noun indicating a certain range of objects or list of a few options to choose from. It carries the meaning of ‘among’ or ‘of (those things)’ or ‘between A and B’.
● 한국 음식 중에서 제가 제일 좋아하는 것은 비빔밥이이에요. (Among Korean foods, bibimbap is my favorite.)
● 지하철하고 택시 중에서 뭐가 더 빨라요? (Which is faster between subway and taxi?)