下列程序运行后，单击命令按钮，窗体显示的结果为( )。
Private Function pl(x As Integer,y As Integer,z As Integer)
pl=2*x+y+3*z
End Function
Private Function p2(X As Integer,y As Integer,z As Integer)
p2=p1(z,y,x)+x
End Function
Private Sub Commandl_Click()
Dim a As Integer
Dim b As Integer
Dim c As Integer
a=2:b=3:c=4
Print p2(c,b,a)
End Sub

A．23

B．19

C．21

D．22