This question tests the pronunciation of '-es' ending after sibilant sounds. Options a, b, and c are pronounced as /ɪz/, while option d is pronounced as /ɪz/ as well, but let's check the base sound. 'House', 'horse', 'course' end in sibilant sounds, 'raise' ends in /z/ which is also sibilant. Actually, all pronounced as /ɪz/. Re-evaluating. Options a, b, c have /ɪz/ after voiceless sibilant sounds [s, ʃ, tʃ, z, ʒ, dʒ]. 'Raise' ends in /z/ which is voiced. Aha! 'Houses', 'courses' end in /s/ sound, 'horses' ends in /s/ sound. 'Raises' ends in /z/. Still all are /ɪz/. Let's check base word ending sound again. 'House' /s/, 'horse' /s/, 'course' /s/, 'raise' /z/. All ending in sibilant sounds, so '-es' should be /ɪz/. Something is wrong here. Let's reconsider options - pronunciation of 's' itself. Options a, b, c, ending 's' is /ɪz/, option d 'raises' - ending 's' is /ɪz/. It seems there is no word with different pronunciation. Re-reading the question, 'underlined part'. Underlined part might be just 's' or 'es' ending. If it's just 's' ending sound itself. 'Houses' /z/, 'horses' /ɪz/, 'courses' /ɪz/, 'raises' /ɪz/. 'Houses' has /z/ sound at the end of base word 'house' and then /ɪz/. 'Horses', 'courses', 'raises' all already end in sibilant sounds and take /ɪz/. 'Houses' - base word ends in /s/ voiceless, so 's' should be /s/ sound, then plural /ɪz/. 'Horses', 'courses', 'raises' base word ends in sibilant, plural /ɪz/. Still not making sense. Let's check transcriptions. houses /ˈhaʊzɪz/, horses /ˈhɔːrsɪz/, courses /ˈkɔːrsɪz/, raises /ˈreɪzɪz/. All end in /ɪz/. Re-interpreting question - underlined part 's' sound at the end of the word sound itself. Houses - /z/, horses - /ɪz/, courses - /ɪz/, raises - /z/. Still not clear. Let's assume the question is faulty and should be asking about something else, maybe base word sound ending. If we focus on the 's' sound in '-es', then 'houses' - /ɪz/, 'horses' - /ɪz/, 'courses' - /ɪz/, 'raises' - /ɪz/. All are the same. Let's assume there's a typo and one of the words should have '-s' plural instead of '-es'. If 'house' was 'mouse', then 'mouses' would be /ɪz/. If 'horse' was 'bus', 'buses' /ɪz/. 'Course' - 'kiss', 'kisses' /ɪz/. 'Raise' - 'dog', 'dogs' /z/. Aha! If 'raises' was 'dogs', then 'dogs' ends in /z/, while 'houses', 'horses', 'courses' end in /ɪz'. No, 'dogs' ends in /z/ sound, 'houses' ends in /ɪz/. Still confusing. Let's re-examine the words and their endings. 'Houses' base 'house' ends in /s/, plural is /ɪz/. 'Horses' base 'horse' ends in /s/, plural is /ɪz/. 'Courses' base 'course' ends in /s/, plural is /ɪz/. 'Raises' base 'raise' ends in /z/, plural is /ɪz/. It seems all pronunciations are the same for the '-es' ending. This question is likely flawed or testing something extremely subtle that is not apparent from the options provided. Given the context is phonetics, and the prompt is about pronunciation differences, and assuming no typos, the question must be about a subtle difference in vowel or consonant sound before the '-es'. Let's pronounce them again carefully. 'houses' /ˈhaʊzɪz/, 'horses' /ˈhɔːrsɪz/, 'courses' /ˈkɔːrsɪz/, 'raises' /ˈreɪzɪz/. The vowel sounds before '-es' are different. 'house' /aʊ/, 'horse' /ɔː/, 'course' /ɔː/, 'raise' /eɪ/. 'Houses' has /aʊ/, while 'horses' and 'courses' have /ɔː/, and 'raises' has /eɪ/. 'Houses' is different in the vowel sound before the plural ending.
