The skeletal system the muscular system and the nervous system i will take other explain one link between the skeletal muscular system and nervous system

 skeletal system and the muscular system, 

Muscles are attached to the skeleton and work assuming that the skeleton is there - for example there is no muscle that makes sure you don't bend the middle of your arm, as it's stable because there is a bone in it. Basically, the skeleton is a scaffolding for the muscles

the skeletal system and the nervous system,

Many nerves run along the skeleton, or even inside the bones and the bones protect the nerves - for example in the spinal cord

the muscular system and the nervous system.

Nervous system controls the muscles! it sends them messages such as "move the muscle now" - and in fact the muscles are directly connected to the skeleton

i believe the answer would be 'd'.

hope this !

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