Answer:
The process of looking up unfamiliar words increases Ron's a. lexicon.
Step-by-step explanation:
Lexicon is a synonym for vocabulary, that is, all the words used by a person. When someone like Ron looks up unfamiliar words, he is enhancing, increasing, his vocabulary - the number of words he understands and is, therefore, able to use. Now that he knows what "wanderlust" means, that word has become a part of Ron's lexicon.