①转动粗准焦螺旋                    ②调节光圈                ③转动细准焦螺旋

④转动转换器                           ⑤移动标本

A．①→②→③→④                                     B．④→③→②→⑤

C．②→①→⑤→④                                     D．⑤→④→②→③