Midwinter in the southern hemisphere comes in June and July, and midsummer comes in December. The opening of spring comes in August and September, and autumn approaches in February and March. But while in the northern hemisphere the difference between the heat of midsummer and the cold of midwinter is somewhat lessened by the changing distance of the sun, in the southern hemisphere this effect is intensified, because the earth comes to perihelion in the southern midsummer. However, on account of the swifter motion of the earth from October to March than from April to September, the southern summer is shorter enough to compensate for the sun’s being nearer, so that the southern summer is practically no hotter than the northern.

In the argument given, the two portions in boldface play which of the following roles?

A. The first is an assertion made by the argument in support of a position; the second states that position.
B. The first is a claim made by the argument; the second qualifies the claim by presenting another assertion.
C. The first is the summary of the argument’s position; the second provides evidence supporting that position.
D. The first presents an example that is contrary to the argument’s position; the second adds another opposing example.
E. The first is a concession that the position the argument establishes is not absolute; the second provides an exception to the argument’s position.