Concept:The vowel sound in "sheath" is the long vowel sound /i:/.Explanation:"sheath" is pronounced as /shi:θ/.The underlined letters "ea" produce the long /i:/ sound.Now check each option for the same vowel sound."meadow" has /e/ as in "red"."beach" is pronounced /bi:tS/ and has the same long /i:/ sound."weather" has /e/ as in "bed"."heart" has /a:/ as in "car".Therefore, "beach" matches the vowel sound in "sheath".Answer:B. beach