Final answer:
The best example of a nurse acting as an advocate is the writing of legislation for insurance coverage for screening colonoscopies, as it demonstrates active policy change efforts for patient care improvements.
Step-by-step explanation:
The scenario that best exemplifies a nurse acting as an advocate is the first one: Writing legislation for insurance coverage for screening colonoscopies. In this case, the nurse is actively seeking to change policies for the betterment of patient care and community health outcomes, which is a central aspect of advocacy. Advocacy involves standing up for the rights and needs of patients and may include activities such as influencing policy, ensuring access to care, and educating patients and the public about health issues. Nurses serve as advocates when they take action to promote what is in the best interest of patients, including taking steps to secure funding for important preventative measures like colonoscopies.