下列VB程序段的功能为：生成n个不重复的随机整数，保存在数组a中，并升序排序。
Const n = 6
Dim a(1 To n) As Integer, f(1 To 10) As Boolean
Dim tmp As Integer, i As Integer, j As Integer, t As Integer
’f数组各元素的初值置为False，代码略
For i = 1 To    (1)  
t = Int(1 + Rnd * 10)
If Not f(t) Then
a(i) = t : f(t) = True
For j = (2)   
If a(j) < a(j - 1) Then
tmp = a(j): a(j) = a(j - 1): a(j - 1) = tmp
End If
Next j
Else
(3)  
End If
Next i
上述程序段3个方框处的表达式分别为

A．（1）n - 1 （2）2 to i    （3）i = i - 1

B．（1）n （2）i to 2 Step -1    （3）i = i - 1

C．（1）n - 1    （2）2 to i    （3）t = Int(1 + Rnd * 10)

D．（1）n （2）i to 2 Step -1    （3）t = Int(1 + Rnd * 10)