For which of the following reasons are late seventeenth and early eighteenth century Chinese records important according to the passage
A．They suggest that the data on which the Maunder minimum was predicated were incorrect.
B．They suggest that the Maunder minimum can not be related to climate.
C．They suggest that the Maunder minimum might be valid only for Europe.
D．They establish the existence of a span of unusually cold weather worldwide at the time of the Maunder minimum.