题目内容：
Howdidthesereservesbeformedwhereitisundertheseatoday? A．Theaveragesealeveldroppedandsomeseawaterinfiltratedintoseabed.
B．Freshwaterisheavierthanseawater.
C．Sealevelincreasedandcoveredsomeareaswithundergroundwater.
D．Someundergroundwaterinfiltratedintoaquifers.
参考答案：
答案解析：