【正确答案】 C

【答案解析】[试题分析] 事实推断题。
[详细解答] 文章第二段谈到The pill is still working in your system when you get up in the morning．This helps account for the fact that you feel tired all day．正因为药效早上仍在起作用，导致你一整天都疲乏。所以答案为C。