Final answer:
Kaido's devil fruit in 'One Piece' allows him to (B) transform into a dragon, granting him immense power and abilities like breathing fire, typical of eastern dragons.
Step-by-step explanation:
The devil fruit that Kaido ate in the anime and manga series One Piece allows him to transform into a dragon. This is confirmed in the series, where Kaido, who is known as one of the Four Emperors in the world of One Piece, showcases the ability to change between his human form and a gigantic, powerful dragon form.
The fruit he consumed is classified as a Mythical Zoan type, which provides him not only the power to transform but also grants him additional abilities that are characteristic of eastern dragons, such as breathing fire.