The United States is composed of ______states and one district, the District of Columbi

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.

A．presenting two competing scientific theories concerning solar activity and evaluating geological evidence often cited to support them
B．giving a brief overview of some recent scientific developments in solar physics and assessing their impact on future climatological research
C．discussing the difficulties involved in linking terrestrial phenomena with solar activity and indicating how resolving that issue could have an impact on our understanding of solar physics
D．pointing out the futility of a certain line of scientific inquiry into the terrestrial effects of solar activity and recommending its abandonment in favor of purely physics-oriented research