Correct option is B
Given Words: CAT, OWN, EYE, SAD
Rule: Change each letter to the next in the English alphabet.

Transformed Words:
CAT → DBU → Contains U (vowel)
OWN → PXO → Contains O (vowel)
EYE → FZF → No vowels
SAD → TBE → Contains E (vowel)
AND → BOE → Contains O, E (vowels)
Total words with at least one vowel = 4
Correct answer is (b) Four.