19. According to the passage, what are the characteristics of sunspot cycles?
(A) During the minima phase of the cycle, there is lower overall irradiance but greater local irradiance, and fewer sunspots.
(B) During the maxima phase of the cycle, there is lower overall irradiance but greater local irradiance, and fewer sunspots.
(C) During the minima phase of the cycles, there is greater overall irradiance but lower local irradiance, and fewer sunspots.
(D) During the maxima phase of the cycle, there is lower local irradiance but greater overall irradiance, and more sunspots.