单项选择题

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