Answer:
Option D.
Explanation:
Crossing over is an important characteristic of meiosis which provides the genetic variation and various allelic combinations present in the offspring. Hence the answer is option D. 
 
        
             
        
        
        
Answer:
Red blood
Explanation:
The bluish color of veins is only an optical illusion. Blue light does not penetrate as far into tissue as red light. If the blood vessel is sufficiently deep, your eyes see more blue than red reflected light due to the blood's partial absorption of red wavelengths.
 
        
             
        
        
        
Manipulative experiments alter levels of a predictor variable (or factor), and then measures how one or more variables respond to these alterations. ... Natural experiments-An observational study in which we take advantage of natural variation that is present in the variable of interest.
        
             
        
        
        
There is misspelled. It should be spelled their
        
                    
             
        
        
        
There is a direct relationship between shell color, presence of banding, and habitat because they greatly affect each other in various ways. 
<h3>Relationship between shell color, presence of banding, and habitat </h3>
Shell colour shows stronger and more consistent variation with habitat than do banding patterns. Yellow colour shells are present at higher frequencies in open habitats than in woods or closed habitats.
While on the other hand, banding serve as camouflage to protect the organism from bird predators so we can conclude that there is a direct relationship between shell color, presence of banding, and habitat.
Learn more about shell here: brainly.com/question/26039758