If you select the WING ANTI-ICE switch on the ground:
A.A.Wing anti-ice control valves open if thrust on both engines is below takeoff warning setting and temperature inside both distribution ducts is below thermal switch activation temperature
B.B.Wing anti-ice control valves open if thrust on either engine is below takeoff warning setting and temperature inside both distribution ducts is below thermal switch activation temperature
C.C.Wing anti-ice control valves open if thrust on both engines is below takeoff warning setting.
正确答案是A