A bit later I （）a group of hiker

A bit later I （）a group of hikers out for a walk.
A、came on
B、came upon
C、came back
D、came up with
【正确答案】：B
【题目解析】：此题考查与come有关的短语，come on开始，进步，进展，加油；come upon偶然遇到（某人、某事）；come back回来，再次流行；come up with想出（办法），提出（建议）。根据句意：过了一会儿，我碰到一群背包客出来散步。可知，应选B