Concept:The underlined letter must produce the same pronounced consonant sound as in the given word.Explanation:In laboratory, the underlined b is pronounced as /b/.Check each option:A. debtor — the "b" is silent.B. thumb — the "b" is silent.C. dabble — the "b" is pronounced /b/.D. subtle — the "b" is silent.Therefore, dabble has the same consonant sound /b/.Answer:C. dabble