单项选择题

单击命令按钮时,下列程序的执行结果为( )。   Private Sub Command1_Click()    Dim a As Integer,b As Integer,c As Integer    a=2:b=3:C=4    Print P2(c,b,A)   End Sub   Private Function P1(x As Integer,y As Integer,z As Integer)    P1=2 * X + y + 3 * z   End Function   Private Function P2(x As Integer,y As Integer,z As Integer)    P2=P1(z,x,y) + X   End Function

A.21
B.19
C.17
D.34