Pick out the sentence which has the same meaning as the following:
The last question was the most difficult.

A sentence can be converted such that the degree of comparison is changed but the meaning of the sentence remains the same.
For example:
- The last question was the most difficult.
- The last question was more difficult than any other question.
Both sentences imply that it was the last question that was difficult as compared to any other questions.
Hence, we conclude that the correct formation is ‘The last question was more difficult than any other question’.