I think this a tough question, and I hesitated between a) and b), but I choose the second answer - Physical Therapist.
Physical Therapists are licensed providers of care, and their educational education has evolved to the point where physical therapists graduate with a doctorate in physcal therapy. Personal trainers have a degree or a certificate. This is not the same.
I think the correct answer is D
The study of the functions of a structure is known as physiology.
2 I have taken that before
