Concept:This question tests your ability to identify whether the letter b produces a real sound or is silent in a word.Explanation:The word womb is pronounced /wu:m/, so the b is silent.The word doubt is pronounced /daut/, so the b is silent.The word public is pronounced /’publik/, and here the b makes a clear /b/ sound.The word thumb is pronounced /θmˇ/, so the b is also silent.Therefore, only public contains the actual /b/ sound represented by the phonetic symbol.Answer:C. public