The spelling of the word "OPABA" can be explained using the International Phonetic Alphabet (IPA) as /oʊˈpɑːbə/. The first syllable is pronounced with a long "o" sound and a diphthong "ow", represented by the symbol /oʊ/. The second syllable has a short "a" sound followed by the consonant "p", represented as /ˈpɑːb/. The final syllable has an unstressed "uh" sound, represented as /ə/. Therefore, the correct spelling of the word "OPABA" reflects its pronunciation using IPA.