I am familiar with this type of question, and I have to say that most of the examples I have encountered are more straightforward, meaning to say: It's easier to decide because the options are very different from each other and the respective text makes it quite obvious. This is one of those cases, where both answers could be argued for easily in a discussion. I would go for B, simply because what stays with me after reading it, is how this woman spends all her energy, of which she has so little left at that point, to teach her children, so she is very devoted to the job.
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