What does the comparison between the country girls and town girls in this passage show?

Read the passage from *My Antonia* by Willa Cather.

> I can remember a score of these country girls who were in service in Black Hawk during the few years I lived there, and I can remember something unusual and engaging about each of them. Physically they were almost a race apart, and out-of-door work had given them a vigour which, when they got over their first shyness on coming to town, developed into a positive carriage and freedom of movement, and made them conspicuous among Black Hawk women. That was before the day of high-school athletics. Girls who had to walk more than half a mile to school were pitied. There was not a tennis-court in the town; physical exercise was thought rather inelegant for the daughters of well-to-do families. Some of the high-school girls were jolly and pretty, but they stayed indoors in winter because of the cold, and in summer because of the heat. When one danced with them, their bodies never moved inside their clothes; their muscles seemed to ask but one thing – not to be disturbed. I remember those girls merely as faces in the schoolroom, gay and rosy, or listless and dull, cut off below the shoulders, like cherubs, by the ink-smeared tops of the high desks that were surely put there to make us round-shouldered and hollow-chested.

A. Both the country girls and town girls did not exercise much because they didn’t have sports in high school.
B. Both the country girls and the town girls got a lot of exercise walking to school.
C. The country girls were stronger and healthier than the town girls because they got more exercise.
D. The town girls were healthier and stronger than the country girls because they had more free time for exercise.