You are presented with the question "Allergic reactions can be caused by" and the following answer choices: 
- animals
 - smoking pipes
 - Sulfur dioxide
 - Chemical energy
 - fur and fat
 - antibodies
 - smoking tobacco
 - Pesticides

Now knowing that antibodies are large, Y-shaped proteins that recognize and bind to antigens and allergic reactions are caused by substances called antigens, choose the best answer.


 

      antibodies   