What is the priority nursing intervention for a patient during the immediate post-operative period?

Q-c_G2Gmn3yaBEtTkkmMk8
E6 Nursing Brunner Adult Health 3SA Vol 1 Part 1 p. 118-120
Practise the full KPSC Staff Nurse - 2016
Attempt every question from this paper in a timed mock, then review the full solution for each one.