Choose the word nearest in meaning to the word given below : Arduous?

Q2vgct35FiQy0RngNJTkku
E6 Physiology Review Sembulingam 5e p. 129-131
Practise the full AIIMS BHOPAL NO- 2018( Shift-2nd)
Attempt every question from this paper in a timed mock, then review the full solution for each one.