Three professional healthsector​

Explanation:

A health professional (or healthcare professional) may provide health care treatment and advice based on formal training and experience. The field includes those who work as a medical doctor (such as family physician, internist, obstetrician, psychiatrist, radiologist, surgeon etc), physician assistant, veterinarian, veterinary technician, veterinary assistant, pharmacist, pharmacy technician, medical assistant, nurse, physical therapist, occupational therapist, dentist, midwife, psychologist, or who perform services in allied health professions. A health professional may also be an expert in public health or community health.

Fields

internist,obstetrician,radiologist

Explanation:

The reason these 3 were picked was because these are all seriously professional health sector's that their uses are even higher than my grandfathers knowledge.