【单选题】

We spend our leisure hours efficiently for higher production, live by the clock even when time does not matter, modernize our homes and speed the machinery of living in order that we can go to the most places and do the most things in the shortest period of time possible. We try to eat, sleep, and talk efficiently.Even on holidays and Sundays, the efficient man relaxes on timetable with one eye on the clock and the other on an appointment sheet.

To squeeze the most out of each shining hour we have shortened the opera, quickened the pace of the movie and put culture in pocket-sized packages. We make the busy bee look like a lazy creature, the ant like a sluggard. We live sixty-mile-minute and the great efficiency smiles.
We wish we could return to that pleasant day when we considered time a friend instead of an enemy; when we did things willingly and because we wanted to, rather than because our timetable called for it,But that of course would not be efficiency; and weAmericans must be efficient.
The phrase that best expresses the main idea of this passage is ______.A．the modern pace
B．our interest in shortened operas
C．how to make the best use of leisure time
D．planning our time scientifically