Concept:The vowel sound in “soul” is the same diphthong used in “boat,” so choose the word that shares that exact pronunciation.Explanation:In “soul,” the letters “ou” make the sound /oʊ/ (British /əʊ/).This is the same vowel sound heard in “boat.”Now check the other words:“how” has the /aʊ/ sound, as in “cow.”“plough” also has the /aʊ/ sound, like “how.”“buoy” (the intended spelling for option D) has the /ɔɪ/ sound, as in “boy.”Only “boat” contains the /oʊ/ sound.Answer:C. boat