Which Statement or Question by the Nurse Manager Demonstrates an Assertive

Which statement or question by the nurse manager demonstrates an assertive approach when communicating with the staff nurse about a patient care issue?

A) "You must assess and document pain status for every patient."
B) "Why haven't you been assessing and documenting pain for every patient?"
C) "Will you please assess and document pain status for every patient?"
D) "Explain why you haven't been assessing and documenting pain for every patient."