Concept:The answer depends on the actual consonant sound(s) of the underlined letters "ph", not on their spelling.Explanation:In "upholstery", the "ph" is not pronounced as /f/. It represents the consonant sounds /p/ followed by /h/. The same sounds occur in "upheaval", where "ph" also gives /p/ + /h/. "Phonetics" is not correct because its "ph" is pronounced /f/. "Reception" and "rehearsal" do not have the matching consonant sequence.Answer:C. upheaval