First, let’s look at the lines we’re dealing with:
the author says that, if Thoreau had a family and no skills, he would have
to work like anyone else, that it was because he only supported himself
and was actually a very talented craftsman that he could live the simple
life. To oppose that, facts would have to state that he actually
did support more than just himself (or that he wasn’t actually skilled).
The answer choice that most directly conveys that fact (that he did support
others) is A.