D 无论什么时候;每当 You use whenever to refer to any time or
every time that something happens or is true.
A 任何一种;不管哪种 You use whichever in order to
indicate that it does not matter which of the possible alternatives happens or
is chosen
A是想提供给对方一个选择,因为说话的人建议要不要下午见面而不是具体几点.