下面程序运行后的结果是( )。
Private Sub Form_Click()
Dim s As Integer，k As Integer,i As Integer，n As Integer
s=1
fori=1 to 3
forj=i to 3
for k=j to istep-1
s=s*k
nextk,J,i
print s
End Sub

A．6

B．72

C．144

D．432