RFC 3270 describes Differentiated Services （Diff-Serv） over Multi-Protocol Label Switching （MPLS）networks. Which model alters Differentiated Services （Diff-Serv） code points set in different DifferentiatedServices （Diff-Serv） domain？（）

• A、Uniform model
• B、Pipe Model
• C、Short Pipe
• D、None of the above will alter Differentiated Services（Diff-Serv）code points set in different DifferentiatedServices（Diff-Serv）domain