Please indicate on the enclosed copy of your order form ______ y

Please indicate on the enclosed copy of your order form ______ you want to place a cash order now.
A、when
B、whether
C、until
D、unless
【正确答案】：B
【题目解析】：句意：请在随函所附的订单副本上注明您现在是否想下现金订单。