Explanation:

- The sentence compares milk to any other food, so a comparative form of “nourishing” is needed.

- Option 1: as nourishing – This suggests milk is equal in nourishment, but isn’t a comparative.

- Option 2: more nourishing – This is the correct comparative form to indicate milk is relatively higher in nourishment.

- Option 3: most nourishing – This suggests milk is the highest in nourishment among all foods, but the sentence structure calls for a comparative, not superlative.

- Option 4: nourishing – This is a simple adjective and doesn’t convey comparison.

Your understanding is correct.