Allergic reactions can be caused by
animals smoking pipes Sulfur dioxide Chemical energy fur and fat antibodies smoking tobacco Pesticides
A B C D E F G H
Allergic reactions are caused by substances called antigens.
Antibodies  can cause allergic reactions
Allergic reactions can be caused by (A) animals (B) smoking pipes (C) Sulfur dioxide (D) Chemical energy (E) fur and fat (F) antibodies (G) smoking tobacco (H) Pesticides