Sven likes to water ski, but can only water ski during the one week each year when he is on vacation. Therefore, he plans to ski every day, for eight hours a day. The first day, Sven skied for eight hours and enjoyed every hour. The second day, Sven slept in and then skied for seven hours, which was fun but not as much fun as the first day. The third day, Sven skied for six hours, but was starting to get a bit bored by the end. The fourth day, Sven skied for four hours and then took a nap. On the fifth day of Sven's vacation, Sven went blueberry picking all day. Sven's total utility ________ with each hour that he skied.
选项：

A:increased;
B:remained constant;
C:first increased than decreased;
D:decreased