单击一次命令按钮后，下列程序的执行结果是 Private Sub Command1_Click() s=P(1) +P(2) +P(3) +P(4) Print s End Sub Public Function P(N As Integer) Static Sum For i=1 To N Sum=Sum+i Next i P=Sum End Function

A．15

B．25

C．35

D．45