1. (2020高三上·衢州月考) 有如下VB程序段：

a(1) = 3:a(2) = 1:a(3) = 3

a(4) = 4 :a(5) = 6

pos = 1 : n = 5

For i = 1 To 10000

    pos = (pos + a(pos) - 1) Mod n + 1

Next i

执行该程序段后，pos的值是（  ）