Explanation:

- Option 1: "about" – This word is not suitable here as it does not convey the intended meaning of quantity or degree.

- Option 2: "hardly" – This implies there is almost nothing to learn, which contradicts the intended message of the sentence.

- Option 3: "quite" – This correctly emphasizes that there is a significant amount to learn from nature. It's an appropriate adverb to show a high degree.

- Option 4: "almost" – This word suggests something is nearly complete or true. It does not indicate a significant amount in this context.