Which describes an interaction within the musculoskeletal system?
a.) when a muscle contracts, a bone will move.
b.) when a bone contracts, a muscle will move.
c.) when a tendon contracts, a ligament will move.
d.) when a ligament contracts, a tendon will move.

The correct answer is A.
Skeletal muscles are connected to the bones with various types of connective tissue like tendons.  Bones and connective tissue lack the structural elements needed for contraction and movement, so the only way to move them is by moving the muscles.The complex structure of the muscle fibers enables the muscles to contract and move, moving the bones at the same time.