Concept:The vowel sound in the underlined part of "manure" is the weak schwa sound /ə/.Explanation:"Manure" is pronounced /məˈnjʊə/.Its underlined vowel letter gives the sound /ə/.Now check each option:A. "party" is pronounced /ˈpɑːti/ — it has /ɑː/.B. "search" is pronounced /sɜːtʃ/ — it has /ɜː/.C. "again" is pronounced /əˈɡen/ — it begins with the same sound /ə/.D. "bad" is pronounced /bæd/ — it has /æ/.Only "again" has the same vowel sound /ə/ as in "manure".Answer:C. again