Final answer:
The nurse collecting data about urinary tract infections is acting in the role of a Researcher, which involves systematic investigation to improve patient care.
Step-by-step explanation:
When a nurse is collecting data about the number of urinary tract infections on the nursing unit, the role they are exhibiting is that of a Researcher. In this role, the nurse engages in systematic investigation, including data collection, for the purpose of improving patient care. This activity is in line with the process of evidence-based practice where clinicians use data and research to inform their clinical decisions and optimize patient outcomes.