The body system that is responsible for transmitting messages from other body parts back and forth to the brain is the

a~ skeletal system.

b~ nervous system.

c~ digestive system.

d~ cardiovascular system.

B. Nervous system. The brain sends waves of information to the body, which travels back up to the brain and gets processed. 

Well if you pick a machine to work on and that's gonna be your exercise if you don't stick to that machine your muscle strength your muscle mass rather will change because you haven't been doing it you change something in your exercise routine which changes your body's form of dealing with things for example you might become weaker or stronger depending on what kind of exercises you do in whether or not the machine you picked actually your muscles grow.

The answer i think would be diet coke