TestKing has five regional offices that are located in different cities. The IT staff is evaluating WAN technologies to interconnect the regional offices to corporate headquarters. Each of the regional offices should be connected to the corporate headquarters in a hub and spoke arrangement using a packet-switched technology. Which of the following WAN technologies will fulfill these requirements?（）

• A、Frame Relay
• B、ISDN
• C、T1 leased lines
• D、Wireless