Concept:The underlined letters stand for the consonant sound /tʃ/.Explanation:In "nature", the letter "t" is pronounced as /tʃ/, giving /ˈneɪtʃə/.In "nation", the letters "ti" are pronounced as /ʃ/, giving /nay-shun/.In "champagne", the letters "ch" are pronounced as /ʃ/, giving /ʃæmˈpeɪn/.In "chameleon", the letters "ch" are pronounced as /k/, giving /kəˈmiːliən/.Only "nature" shares the same /tʃ/ sound as the underlined letters.Answer:A. nature