Answer:
 a. shorten
Explanation:
Inability or failure for joints to move through their entire range of motion is caused by constrictions. These constrictions often results when the excess adipose tissues that surrounds the muscles and ligaments are not in required adequate proportion. These constrictions can be caused by ageing, fatigue, muscular diseases etc. As a result of these constriction in the joints, let say for example, the knee joint, the muscle and ligaments tends to shorten in length.
 
        
             
        
        
        
The answer is guard cells. 
Guard cells are cells surrounding each stoma. They help regulate the rate of transpiration by opening and closing the stomata. They are specialized cells in the epidermis of leaves, stems and other organs that are used to control gas exchange. They are produced in pairs with a gap between them that forms a stomatal pore (stoma).
        
                    
             
        
        
        
Answer:
refrain from using or disposing of (something); retain for future use.
Explanation:
 
        
             
        
        
        
The Discovery<span> of Radioactivity. In 1896 </span>Henri Becquerel<span> was using naturally fluorescent minerals to study the properties of x-rays, which had been</span>discovered<span> in 1895 by Wilhelm Roentgen</span>
        
             
        
        
        
Biomass is plant or animal material used as fuel to produce electricity or heat. Therefore i think the answer is plants!