• How to express difficulties on the survey?



I would like to answer to the survey on difficulties, but I am wondering which I should mark for the most difficult task, 1 or 9 (or other).

Firstly, I thought that the numbers stand for levels, and that 9 stands for the most difficult task.
On the other hand, it appears as a ranking(leaderboard) and 1(st) may be the most difficult task.

Which is correct, or are there any other interpretations?