NO.PZ2018062021000004
问题如下：
A long-short positions are used in:
选项：
A.
Both event-driven and macro hedge fund strategies.
B.
Only event-driven strategies.
C.
Only macro hedge fund strategies.
解释：
A is correct.
Event-driven 和macro hedge fund strategies都是对冲基金的投资策略，而对冲基金往往同时做多做空，所以A符合题目描述特征；B选项和C选项，都说是二者只有一个适用，所以都不正确
四个策略，都是同时做多做空吧
