A crystal is any solid that has an organized structure. ... So it is a prerequisite to be a crystal in order to be a mineral. All minerals, therefore, form crystals. On the other hand, there are crystals that are not minerals, because they are not naturally occuring, or because they are not inorganic
Source: http://www.geologyin.com/2016/03/what-is-difference-between-minerals-and.html?m=1
        
             
        
        
        
Hello! The answer is D
A good note for these is when there are three elements, one being a singular element and another a compound and there’s a single switch, this could show a single-displacement 
Have a good day gamer.
        
             
        
        
        
I think that work is being done on the books because they are being moved to their proper location and they will be sorted properly rather than lying on a table. Without lifting or carrying, you could sort the books by their genre or title name on the bookshelf so it will be sorted much more efficiently. 
I’m not sure if this is the answer you are looking for but I hope it helps :)