Concept:The underlined vowel sound in the given word is the short central vowel ∧, common in words like dumb.Explanation:The word dumb is pronounced /d∧m/, with the vowel sound /∧/.Now check each option for the same vowel sound:A. comb is /k∘m/ with a long /∘/, not the same.B. pupil has /ju/ in the second syllable, not /∧/.C. urban is pronounced /′a:b∘n/ or with a schwa, not the same.D. month is pronounced /m∧nθ/, containing the vowel sound /∧/.Therefore, the word that shares the same vowel sound is month.Answer:D. month