Occasions are quite rareI have the time to spend a day with my kids.A who B which C why D

问题补充：

Occasions are quite rareI have the time to spend a day with my kids.

A who B which C why Dwhen

答案：

解析：D解析又先行词occasions可判断选when 且when 引导的定语从句与先行词分隔开了。