The answer is "Vacuole". I hope this help!
        
             
        
        
        
1.Most aquatic animals have fins or paddles that help them swim
2. Skin is usually slippery and soft
        
             
        
        
        
A or C 
Explanation:
Gas does not have a volume correct me if im wrong 
 
        
             
        
        
        
<span>Large changes in allele frequencies can occur in a short time - any changes in frequency, occurring as a result of random chance, would have a proportionally larger effect in a small population. </span>
        
             
        
        
        
D because gravitational force cannot pull or push