Because of their high rate of mutation. They also can be hard to track because they infuse their DNA into your body cell DNA and can lay dormant and undetected for years.
        
                    
             
        
        
        
Al's cat is displaying territoriality by marking his territory by marking territory with urine and scratches. 
Territoriality
Territoriality is the defense of the area where an organism lives. The marked area is often regarded as the territory of the animal living there. Al's cat is marking its territory by urinating on the plants and scratching them. Other animals that enter the territory of the cat will be able to know that the territory is not theirs and keep themselves away from the same. If an animal invades the territory of another animal it might get attacked by the animal whose territory it just invaded.
Marking the territory often comes with many perks as the animal is able to lay claim to the food, nest locations, shelter, interactions with mates, etc. The animal is able to monopolize the space in which they live. 
Learn more about territoriality here:
brainly.com/question/806271
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C) mechanical energy. 
hope it is correct
        
                    
             
        
        
        
Answer:
Cell types I and III are animal and fungal cells, which are most closely related since they are eukaryotic cells that are heterotrophic. Eukaryotic cells include plants, animals, fungi, and protists.
Explanation: