By collecting quotations from a range of authors, he augmented the vocabulary.

• A. By collecting quotations from a range of authors.
• B. He reduced the vocabulary to a few common words.
• C. He relied only on modern authors.
• D. He excluded non-poetic sources.

Answer: (A)

Enhancing vocabulary comes from exposure to diverse language. When you collect quotations from a range of authors, you encounter words in different contexts, with varied connotations and uses, which broadens your lexical repertoire and strengthens your ability to recall and apply terms precisely. This directly matches the idea of expanding vocabulary, making it the best fit for the sentence. The other options describe narrowing or restricting sources—reducing vocabulary to a few words, relying only on modern authors, or excluding non-poetic sources—which would not lead to a broader, richer lexicon.