What does the passage mainly discuss?

The passage mainly discusses that____
A. teachers' universities lack courses about class management
B. absence of different learning approaches leads to new teachers' lack of class control skills

My answer is A, but the given answer is B. But in Option B, I think "learning approaches" is irrelavant. What do you think?

Back in the '60s, when I attended the Queen of the Rosary school in suburban Chicago, classroom management was not an issue. We had more than 35 kids in a class, but even first graders knew you sat with your hands folded, eyes on the board, and mouth shut. If you got out of line, you might be sent to the corner. One nun had an amazing pitching arm. She would spin away from the blackboard and bean a slacker with a fully loaded eraser. It didn't hurt. But it was effective.
Now when you talk to new teachers—which I do regularly as an education reporter—their biggest complaint is that no one teaches them how to control a classroom. For the small fortune they spend to get a teaching degree, they get plenty of pedagogy ("Reflections on Learning" is a typical course name), which they generally don't use. But their professors never seem to get around to teaching "Keeping Kids Under Control 101." Student-teaching stints are typically done in "middle-class districts that are well ordered," says Aaron M. Pallas, professor of sociology and education at Teachers College at Columbia University, and few colleges offer practical training for those planning to work in tougher settings.
The solution is probably not to encourage teachers to bean kids with erasers. But something is needed. Jennifer Scoggins, 32, a New York teacher currently working on her Ph.D., said she had no chance to succeed when she began her first teaching job in 2001. She was asked to take over a second-grade class in Harlem midyear—after several other teachers had given up. The kids were out of control when she arrived, and things never improved. "Chairs were being thrown, kids were stabbing each other with pencils," she said. "I felt absolutely like a total failure. The only thing I was proud of was that I never cried in front of the kids. But I cried everywhere else: in supply closets, on the subway, at home." Even though Scoggins had earned a master's in education, she said, "very practical things were never taught."
Education Secretary Arne Duncan has acknowledged what a huge issue classroom management has become. To help improve the situation, the federal government recently dedicated $21 million to a fledging network of 28 teacher-residency programs (modeled on medical residencies) to give new teachers hands-on training in a real classroom. Later this year Duncan plans to distribute another $100 million in grants to expand the idea further.
No such programs were available to Scoggins, who thought about quitting teaching altogether after her disastrous first year. But, she said, "I had never been interested in doing anything else." So she tried again at a different Harlem school, and was assigned to an experienced team that gave her support. "If I was having a problem with a child, someone would come into the room to observe and give me advice," she said. "I felt like they had my back." Lots of new teachers wish they could say the same.