有如下VB程序段：

i = 0: j = 1

Do While j <= 5

  If a(j) <> 0 Then i = i + 1: a(i) = a(j)

  j = j + 1

Loop

For j = i + 1 To 5

  a(j) = 0

Next j

数组元素a(1)到a(5)的值依次为“0,20,0,4,31”，执行该程序段后，a(1)~a(6)各元素的值依次为（  ）

A、4,20,31,0,0

B、31,20,4,0,0

C、0,0,20,4,31

D、20,4,31,0,0