The response that BEST helps to complete the R.A.C.E. strategy for the prompt about the usefulness of etymology is:
"The knowledge of etymology can help readers because it provides the history of the word and can help readers understand the meaning. Therefore, readers can apply that knowledge to other words with the same pattern to define unfamiliar words."
Reasoning: This response effectively restates the importance of etymology, answers the prompt directly, cites evidence about how understanding the history of a word aids comprehension, and explains how this knowledge can help in deciphering unfamiliar words based on their root patterns. It presents a clear and concise argument that adheres to the components of the R.A.C.E. strategy.