Concept:The correct answer must have the same vowel sound as the underlined letters, not the same spelling.Explanation:The underlined letter(s) in the given word produce the vowel sound /3:/.Now compare the options by their pronunciation, not by their written form.“Pet” is pronounced /pet/, so its vowel sound is /e/.“Sword” is pronounced /so:d/, so its vowel sound is /o:/.“Deed” is pronounced /di:d/, so its vowel sound is /i:/.Only “Worth”, pronounced /wε:θ/, contains the vowel sound /ɜː/.Therefore, “worth” matches the required vowel sound.Answer:B. worth