单项选择题

在窗体上画一个名称为Command1的命令按钮和一个名称为List1的列表框。如图1所示程序的功能是:单击命令按钮后,程序用"筛选法"求出1~100之间的全部素数。将其素数在列表框中显示出来。根据题意,填空处应该选择________。


Option Base 1
Dim a(100)As Integer
Private Sub Command1_Click( )
  n = 100
  For i = 2 To Sqr(n)
    For j = i + 1 To n
      If j Mod i = 0 And a(j)<> 0 Then a(j)= 0
    Next j
  Next i
  For i = 1 To n
    If a(i)<> 0# Then      
  Next i
End Sub
Private Sub Form_Load( )
  For i = 1 To 100
      a(i)= i
  Next i
End Sub