what are the different types of nursing fields?
['Registered Nurse (RN) ... ', 'Cardiac Nurse. ... ', 'Certified Registered Nurse Anesthetist (CRNA) ... ', 'Clinical Nurse Specialist (CNS) ... ', 'Critical Care Nurse. ... ', 'ER Nurse. ... ', 'Family Nurse Practitioner (FNP) ... ', 'Geriatric Nursing.']