— I'm sorry I stepped outside for a smoke. I was very tired.

— There is no _____  for this while you are on duty.[ ]

A. reason

B. excuse

C. cause

D. explanation

现券买卖市场中允许成交的最小成交券面总额是多少？（）

A、1万

B、10万

C、100万

D、1000万