Wireless waste from cell phones, pocket PCs, and music players ______ special problems because they have toxic chemicals in batteries and other components.

A．He cannot remember what he has done but can remember trying to learn.
B．He cannot do something new but he can remember doing it.
C．He suffers from a bad memory and lack of motor skills.
D．He suffers from a poor basal ganglia and has intact explicit memory

A．at the mercy of
B．in accordance with
C．under the guidance of
D．by means of