单项选择题

At dawn one morning in early May, Sean Cosgrove is stashing piles of maps, notes and photocopied documents in his gym bag before heading for West Milford High, a rural school in northernmost New Jersey. On his 30-minute commute, the young former investment banker tries to dream up new ways of lifting the monumentally forgettable Mexican War off the textbook page and into his students’ imaginations. Can he invoke the storied memories of Robert E. Lee, who cut his first military exploits on the plains of Veracuz— or will he be met with thundering responses of "Who’s Lee" Should he raise James K. Polk out of the mystic chords of memory, and hope, for a nanosecond, that the kids will care about the first U. S president who stepped aside because he’d accomplished everything he wanted Let’s think some more. Well, there’s always the Alamo. And hey, isn’t that the teachers’ parking lot up ahead
It’s never an easy task. These big kids in big jeans and ball caps, come to his history classes believing that history is about as useful as Latin. Most are either unaware or unimpressed that the area’s iron forges once produced artillery cannon for George Washington’s army. Their sense of history orbits more narrowly around last month’s adventures on "ShopRite Strip", the students’ nickname for downtown West Milford, once a factory town, now a Magnet for middle-class vacationers.
Cosgrove looks uncommonly glum as the thumbs through a stack of exams in the teachers’ lounge. "I can’t believe anyone in my class could think John Brown was the governor of Massachusetts," moans Cosgrove, 28, pointing to one student’s test paper. He had to be sleeping for days on end. "The same morning, students in his college bound class could name only one U. S. Supreme Court justice—Clarence Thomas. All his wit, energy and beyond-the-textbook research can’t completely reverse the students’ poor preparation in history, their lack of general knowledge, their numbness to the outside world. It’s the bane of history teachers at every level. When University of Vermont professor James Loewen asked his senior social-science majors who fought in the Vietnam War, 22 percent answered North and South Korea. Don’t these kids even go to the movies
What’s the meaning of the word "bane" in the 6th line of the last paragraph