单项选择题

下列程序段的执行结果为 ______。 Dim m(3,3)As Integer Dim i As Integer Dim j As Integer Dim x As Integer For i=1 To 3 m(i,i)=i Next For i=0 To 3 For j=0 To 3 x=x+m(i,j) Next Next Print x

A.3
B.4
C.5
D.6