Answer:
D. body mechanics
Step-by-step explanation:
The correct answer would be that Jake is writing specifically about body mechanics.
Body mechanics is a general term used to describe how the body system coordinates it muscles, bones, and joints during body activities such as sitting, walking, standing, bending, sleeping, etc.
The study of body mechanics include, but not limited to how the measure of force on the shoulder joint causes it to rotate (torque), especially during activities involving the movement of the shoulder such as lifting of objects.
Hence, the correct option is D.