下列程序的功能是统计100-999之间的水仙花数的个数,(水仙花数是指该数等于各个数位上的数的立方和,如水仙花数153=13+53+33),则括号中的程序代码应为( ) Private Sub Command1_Click() Dim a As Integer, b As Integer, c As Integer, d As Integer For a = 1 To 9 For b = 0 To 9 For c = 0 To 9 d = a * 100 + b * 10 + c If ( ) Then Print d Next c Next b Next a End Sub