D is the answer to the question
        
             
        
        
        
Answer:
Clearcutting removes all the trees within a certain area at one time. Shelterwood cutting also removes all the trees in an area, but does it in stages over several years. Seed-tree cutting removes all the trees except for a select number of mature trees that can then reseed the area.
Explanation:
Hope that helps!
 
        
             
        
        
        
Crossing over is essential for the normal segregation of chromosomes during meiosis. Crossing over also accounts for genetic variation, because due to the swapping of genetic material during crossing over, the chromatids held together by the centromere are no longer identical.
I just found this on google
 
        
             
        
        
        
I think it is liqid but i dont know realy.