A．Two detectives investigating the case had tested positive for traces of radiation.

B．The ex-wife and the former mother-in-law of the spy were also poisoned.

C．The Russian businessman who met the former spy in London has fallen ill.

D．There is a high degree of probability that it is polonium that killed the spy.

下列（）对重金属的吸收累计最低。

A.小麦

B.玉米

C.水果

D.蔬菜