Correct Response: C. The words listed all contain the regular past-tense inflection -ed. The ending is spelled the same way in all three cases, but the ending is pronounced differently in each word. In the word watched, the -ed ending is pronounced /t/. In the word wanted, the -ed ending is pronounced [ǝd]. In the word warned, the -ed ending is pronounced /d/. Option A is incorrect because the three words illustrate that a single spelling of the ending can be pronounced three different ways. Option B is incorrect because none of the words contain an open syllable and thus do not illustrate characteristics of open syllables. Option D is incorrect because the syllabication guideline given is relevant to only one of the words (the word wanted).
