I chose option B because I assumed the teachers had simply not considered the approaches they used. The passage does say that their knowledge was somewhat restricted and they simply concentrated on what works, but I returned to paragraph 3 and realized this telling sentence: “tendency of teachers to evaluate events rather than review the contributory factors in a considered manner.” This indicates that the actual problem was that they failed to sit back and consider what caused the events, which corresponds with option C and that is the correct answer.