What word could replace the underlined word in sentence 11, reproduced here: "In fact, it may be argued that studying the humanities helps augment the learning and understanding that comes with those 'real' sciences."

The word enhance is a synonym of augment when it is seen as an improvement or embellishment or support in the understanding of the scientific type of knowledge. The other two word choices are antonyms and would suggest that studying humanities may be harmful, which is not the argument the author is trying to make.