FiElDs FounD thAt whEn thE BACtEriA ACCountED For 100 pArts pEr million oF thE grAin, thE BEEtlEs' supErCooling point ______.
A．rosE By 4℃
B．DroppED By 4℃
C．rosE By 5℃
D．DroppED By 5℃