Explanation:

- Option 1: We enjoyed (1)

- The sentence seems correct in structure unless specifically pointing out what was enjoyed.

- Option 2: much at (2)

- The phrase should be "very much" for proper usage as an adverbial modifier. The word "much" alone is often used with negative sentences or questions.

- Option 3: the hill-station (3)

- The phrase is grammatically correct referring to a location.

- Option 4: No error (4)

- There is an error in the sentence, specifically in option 2. Therefore, this option cannot be correct.

Correct Answer: Option 2, 2