单选题
[阅读理解]The problem of leisure is new. Until very recent times people worked each day to the limit of their strength. Of course there were always a privileged few who had leisure； but most men had to work 12， 14， or even 16 hours a day， six days a week. As late as 1840 the average factory worker labored 72 hours a week. “Sunup to sundown” was the farmer's day， or as another phrase puts it， “from can to can't.”
The phrase “from can to can't” means ______.
A.from beginning to end
B.from birth to death
C.from morning to night
D.from time to time
正确答案：C
答案解析：从本段最后一句话可知，这个短语与“Sunup to sundown”同义，即日出到日落，也就是从早到晚。