阅读下列材料，从每题所给的A、B、C、D四个选项中选出最佳选项。
I've worked in the factories surrounding my hometown every summer since I graduated from high school, but making the transition between school and full-time blue-collar work during the break never gets any easier. For a student like me who considers any class before noon to be uncivilized, getting to a factory by 6 o'clock each morning is torture(折磨). My friends never seem to understand why I'm so relieved to be back at school or that my summer vacation has been anything but a vacation.
There're few people as self-confident as a college student who had never been out in the real world. People my age always seem to overestimate（过高估计） the value of their time and knowledge. In fact, all the classes did not prepare me for my battles with the machine I ran in the plant, which would jam whenever I absent-mindedly put in a part backward or upside down.
The most stressful thing about blue-collar life is knowing your job could disappear overnight. Issues like downsizing and overseas relocation had always seemed distant to me until my co-workers told me that the unit I was working in would shut down within six months and move to Mexico, where people would work for 60 cents an hour.
After working 12-hour shifts in a factory，the other opinions have become only too clear. When I'm back at the university, skipping classes and turning in lazy rewrites seems too irresponsible after seeing what I would be doing without school. All the advice and public-service announcements about the value of an education that used to sound stale now ring true.
These lessons I'm learning，however valuable, are always tinged with a sense of guilt（愧疚）. Many people pass their lives in the places I momently work，spending 30 years where I spend only two months at a time. "This job pays well, but it's hell on the body, " said one co-worker. "Study hard and keep reading，" she added.
My experiences in the factories have inspired me to make the most of my college years before I enter the real world for good.