Select the best way to revise the following sentence to achieve gender-neutral, unbiased language while maintaining pronoun agreement.
when a nurse becomes too emotionally attached to her patients, it becomes difficult for her to do her job effectively.
a.
no change is needed; the sentence is fine as it is.
b.
when nurses become too emotionally attached to their patients, it becomes difficult for him or her to do his or her job effectively.
c.
when a nurse becomes too emotionally attached to his or her patients, it becomes difficult for the nurse to do an effective job.
d.
when a nurse becomes too emotionally attached to their patients, it becomes difficult for them to do their job effectively.