a(1)=2

For i=2 to 7

a(i)=a(i-1)*2-1

Next i

i = 1 : j = 7

Do While i <= j

m =（i + j）\ 2

If a（m）= Key Then Exit Do

If Key < a（m） Then j = m - 1 Else i = m + 1

Loop

若key的值为15，则程序执行结束后，j的值为（  ）

Private Sub Command1_Click()

 Dim i As Integer

 Dim a(10)As Integer    ‘①

 For i=1 To 10    ‘②

  a(i)=Rnd* 100    ‘③

 Next i

 Label1.Caption=Str(a(i))    ‘④

End Sub

Dim c As Integer,a(0 To 5) As Integer

For i = 1 To 5

  a(i) = i

Next i

c = 0

For i = 1 To 5

  x = Int(Rnd * 5 + 1)

  If a(x Mod 5) = i + 2 Then c = c + 1

  If c = x Then Exit For

  i = i - 1

Next i

运行该程序后，变量c的值不可能是（  ）