在允许缺货的情况下，确定经济进货批量必须满足的惟一条件是( )。

A．缺货成本等于相关储存成本

B．相关储存成本等子相关进货费用

C．相关储存成本与相关进货费用之和最小

D．相关储存成本、相关进货费用与缺货成本之和最小

When you phoned me, I was having a meeting, otherwise I _____ your call.[ ]

A. answered

B. would answer

C. had answered

D. would have answered