—You probably won't need to call Joe, but take his number, just .
—Thanks a lot.
A. at random
B. in return
C. in case
D. by heart
网友回答
A. at random
B. in return
(答案→)C. in case
D. by heart
解析： ——你可能不需要给Joe打电话，不过还是记下他的电话号码吧，以防万一。——谢谢！in case“以防万一”，符合语境。