You are the network administrator for ExamSheet. You are configuring a network consisting of 100 client computers and six subnets for the ExamSheet’s new office. You configure the first two subnets and configure client computers on both subnets for testing. You test the initial configuration and discover that not all of the client computers can communicate with each other. The two subnets are show in the following diagram.  All client computers must be able to communicate with each other. What should you do? （）

• A、Change the subnet mask of all the client computers and on the two gateways to  255.255.255.240. 
• B、Change the subnet mask of all the client computers and on the two gateways to  255.255.255.255. 
• C、Change the IP address for Gateway2 to 131.107.5.214 and the IP address for ExamSheet21  to 131.107.5.210. 
• D、Change the IP address for ExamSheet11 to 131.107.5.190 and the IP address for  ExamSheet12 to 131.107.5.191.