单项选择题

A.28℃+1℃;观察并记录培养至第5d
B.28℃+1℃;避光培养,观察并记录培养至第5d
C.25℃+1℃;在培养48h后,即开始每日观察平板,培养7d结束
D.25℃+1℃;避光培养,在培养48h后,即开始每日观察平板,培养7d 结束