Every time a child visited a cousin who has two

cats, the child’s eyes turned red, itched, and

began to water. Then, the child began to have

trouble breathing. It is most likely that the child

reacted this way because

(1) normally harmless cat antigens stimulated

the immune system

(2) it is difficult for the respiratory system to

filter cat antigens out of the inhaled air

(3) cat antigens are a health hazard, since they

always cause disease

(4) cat antigens stop the immune system from

making antibodies, so bacteria cause these

responses