According to the author, scientists do not believe allergies are solely caused by heredity because _______. (Text 3B)

A、somanypeoplehavedevelopedallergiessoquickly;
B、therearesomanynewtypesofallergiestoday;
C、allergiescanonlybetransmittedbyoneparentindicatesthatallergies;
D、thesymptomsofallergiesaresomuchmoreseveretoday