在窗体中添加一个通用对话框Commondialog1和一个命令按钮Command1，当单击按钮时，打开颜色对话框，能实现此功能的程序段是

A．Private Sub Command1_Click() CommondialogShowOpen End Sub
B．Private Sub Command1_Click() Commondialog1.ShowColor End Sub
C．PrivateSubCommand1_Click() Commondialog1.ShowOpen Commondialog1.ShowFont End Sub
D．Private Sub Command1_Click() Commondialog1.ShowColor Commondialog1.ShowHelp End Sub