Final answer:
The correct answer is 'puffier than cirrus clouds'.
Step-by-step explanation:
The correct answer is: 'puffier than cirrus clouds'.
'Puffier' is the comparative form of the adjective 'puffy' and is used to compare two things. In this case, we are comparing cumulus clouds with cirrus clouds.
Example: Cumulus clouds, which are found at low altitudes, look puffier than cirrus clouds because they have a more rounded and fluffy appearance.
Learn more about Comparative adjectives in English