单项选择题

The author focuses primarily on ______.

A．two competing scientific models concerning the sun's magnetic field
B．an overview of some recent scientific developments in solar physics
C．the reasons why a problem in solar physics has not yet been solved
D．the difficulties involved in linking terrestrial climate with solar activity

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单项选择题

According to the passage, for which of the following reasons are the late seventeenth-and early eighteenth-century Chinese records important

A．They disprove the reality of the Maunder minimum.
B．They suggest that the Maunder minimum cannot be related to climate.
C．They verify the existence of a span of unusual cold during the Maunder minimum.
D．They show that the European observations are of dubious statistical significanc