集合P＝{x|2kπ≤α≤(2k＋1)π，k∈Z}，Q＝{α|－4≤α≤4}．则P∩Q＝(　　)

A．∅

B．{α|－4≤α≤－π或0≤α≤π}

C．{α|－4≤α≤4}

D．{α|0≤α≤π}