My question is about which context clue best helps define the word sinewy.
Right.
Yes, that's correct! The word that describes the old bow's sinewy strings is "strong". In the given sentence, it is mentioned that the old bow's strings shot the arrow more than 1,200 yards, which implies that the strings have enough strength to propel the arrow over such a long distance. To determine the answer, you could gather clues from the sentence, paying attention to the use of the words like "frail and weak" to describe the bow and the fact that the arrow is shot a considerable distance. This suggests that the bow's sinewy strings must possess strength to generate enough force to launch the arrow over 1,200 yards.
