Acquired immunity is the type of immunity that exists when a person is exposed to an antigen and subsequently makes antibodies against the antigen. 
Immunity is the defense mechanism of the nervous system to avoid pathogens affecting the body and making it sick. There are two major types of immunity: innate and acquired. Innate immunity is the kind of immunity present in the human body by birth. Whereas, acquired immunity is gained over time. 
Acquired immunity specifically promotes the antibodies or lymphocytes to inhibit the action of pathogens when it encounters one. It is further categorized into two types: active and passive immunity. 
Active immunity indulges in the primary response to a pathogen. It produces antibodies to fight against it and preserves some to fight against the same pathogen encountered for the second time. Passive immunity, in addition, involves the medications prescribed to enhance immunity. 
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Answer:
A.The hole in the ozone layer
Explanation:
• Montreal protocol is an international treaty that was signed to control the use of substances that are resulting in the depletion of the ozone hole. 
This treaty was signed in the year 1987 and became effective form 1989.
• Since the time that this treaty has come into force, there has been a significant improvement in the ozone hole that was observed over Antarctic as it's size has decreased. 
• This improvement has been possible because the treaty helped to phase out chemicals such as chlorofluorocarbons, carbon tetrachloride, etc. that are responsible for ozone hole depletion.
 
        
             
        
        
        
Theories basic to all of the life sciences include the cell theory because all living things are made up of cells.
        
             
        
        
        
Answer:tropical rainforest 
Explanation: Is wet and got