有如下VB程序段，已知字符“A”的ASCII码值为65，则在文本框Text1中输入"abXY"，s1的值最终是（    ）

s = Text1.Text: n = Len(s)

For i = 1 To n

  c = Mid(s, i, 1)

If c >= "a" And c <= "z" Then t = Asc(c) - 32 Else t = Asc(c)

  s1 = s1 + Chr(65 + (t - 63) Mod 26)

Next i

A、CDZA

B、cdZA

C、ZACD

D、ZAcd