Answer:
D or A its up to u i know its not b or c cuz im not dumb UwU
Explanation:
 
        
                    
             
        
        
        
Answer: An antigen 
Explanation: 
A molecule that evokes immune response in the body of an organism is known as antigen. These substance can be protein, carbohydrates, lipids when asked for chemical nature.
Physically these substance can be dust particles, smoke, pollen grains, some food particles. Antigen can be defined as the substance that tends to produce immune response by the immune system of the body.
Hence, the correct answer is option D
 
        
             
        
        
        
Answer:
some of it I believe is the correct answer for that question 
 
        
             
        
        
        
Answer:
faced a struggle for survival
Explanation:
The woolly mammoths became extinct, unlike the other species, because the woolly mammoths faced a struggle for survival due to changing of environmental conditions. Global warming is the main cause of extinction of woolly mammoth which destroy their habitats about 10,500 years ago. The environmental conditions are not favourable for them so they faced struggle for survival which causes extinction of woolly mammoth.
 
        
             
        
        
        
The correct answer is <span>a. fibrous carcinogen. </span>