Answer:
Sexual reproduction produces genetic variation in offspring.
Explanation:
 
        
             
        
        
        
Organ System, Organ coll, tissue
        
             
        
        
        
Answer:
Endoderm
Explanation:
The embryo has three germ layers. The ectoderm, mesoderm, and endoderm. The endoderm is the innermost layer. Other than the endocrine glands, the other tissues that develop from the endoderm are the gastrointestinal tract, urinary and auditory system, and the respiratory tract. 
 
        
             
        
        
        
The change in foot shape making the feet wider and longer than the hands and the curvature of the spine also adapted to it