What foundational skill is assessed in the Vocabulary section related to word structure?

The correct answer focuses on understanding prefixes, suffixes, and root words, which are essential components in word structure. This foundational skill allows learners to dissect unfamiliar words by breaking them down into manageable parts, enhancing their vocabulary and reading comprehension. By recognizing the meanings of prefixes and suffixes, students can make educated guesses about the meanings of new words, thereby expanding their vocabulary more effectively.

The other choices, while related to language skills, do not concentrate specifically on word structure in the same way. Understanding grammar rules, for example, pertains more to sentence formation rather than how individual words are constructed. Recognizing synonyms and antonyms is important for vocabulary enhancement but does not directly involve the structural analysis of words. Evaluating sentence structure focuses on how words fit together to form sentences, rather than the breakdown of words themselves. Thus, the focus on prefixes, suffixes, and root words directly supports the intended assessment of vocabulary related to word structure.