A customer requires a 2-way solution now that will be the easiest and least disruptive to upgrade to a 4-way in the future.  Which of the following solutions best matches these requirements？（）

• A、p630 2-way Active 2-way Inactive
• B、p655 2-way Active 2-way Inactive
• C、p5-520 2-way Active 2-way Inactive
• D、p5-550 2-way Active 2-way Inactive