请选择DCBA3S'v0o;H9n,j;x5j3C7sBirds ________ when there isn’t enough food for them．8E:n/S,]4C1F7L
A． starve8E:n/S,]4C1F7L
B．are starving8E:n/S,]4C1F7L
C．starved8E:n/S,]4C1F7L
D．starves8E:n/S,]4C1F7L