The answer is Thermal Energy :)
 
        
                    
             
        
        
        
I think it's Letter c.13 if I'm not mistaken
        
             
        
        
        
Answer:
 Tendons connect the skeletal system to the muscular system by attaching muscle to bone. When muscle contracts, the tendon acts on the bone, causing movement. Joints, the point at which two or more bones connect, can be fixed, slightly movable, or freely movable. 
 
        
             
        
        
        
The gas molecules move between the system and the surroundings follow PV=nRT.
<h3>What are molecules?</h3>
The smallest particle of a substance has all of the physical and chemical properties of that substance.
An increase in pressure pushes the molecules closer together, reducing the volume. If the pressure is decreased, the gases are free to move about in a larger volume.
In the kinetic theory of gasses, increasing the temperature of a gas increases in average kinetic energy of the molecules, causing increased motion.
The reduction in the volume of the gas means that the molecules are striking the walls more often increasing the pressure, and conversely if the volume increases the distance the molecules must travel to strike the walls increases and they hit the walls less often thus decreasing the pressure.
At constant temperature and pressure the volume of a gas is directly proportional to the number of moles of gas. At constant temperature and volume the pressure of a gas is directly proportional to the number of moles of gas.
Learn more about molecules here:
brainly.com/question/14130817
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