葡萄胎清宫术后3月， * * 不规则流血，子宫稍大，尿HCG（+），胸片示双下肺有多处片状阴影。最可能的诊断是

A．葡萄胎残留

B．先兆流产

C．异位妊娠

D．绒毛膜癌

E．侵蚀性葡萄胎

Which of the following statements regarding marginal costs (MC) and average variable costs (AVC) is most accurate（）

A. MC = AVC when AVC is at its minimum.

B. MC ＜ AVC when AVC is at its minimum.

C. MC = Average total cost when AVC is at its minimum.