Why is A right?

Hi @ChristianJM, This a tricky one! There is a specific part of the passage which is helpful (described below), but understanding the general tone of the passage is probably the most important thing to do in getting this question right. The most helpful part of the passage can be found at lines 35-41. These lines tell us that we make such fast introspective inferences that we fail to notice them and this leads us to assume that we are perceiving something directly. Answer (A) is correct because it reflects the idea, found throughout the passage, that humans are so used to their inferences that they fail to notice them occurring. Similarly, an anthropologist is so used to his own culture that he fails to notice its workings and can't describe them.