Concept:The answer depends on the target vowel sound shown by underlined letters, but that reference word is missing from the question.Explanation:You must compare the vowel sound in each option with the underlined letters of a given word. That word is not provided here. Option A "yell" contains the vowel sound /e/. Option B "bye" contains the diphthong /aɪ/. Option C "quay" is pronounced /kiː/ in WAEC/UK English, giving the vowel sound /iː/. Option D "toil" contains the diphthong /ɔɪ/. Since there is no underlined word to define the required vowel sound, none of the options can be chosen correctly.Answer:The correct option cannot be determined from the information given in the question.