A network administrator provides an IP address of 128.135.0.142 and a subnet mask of 255.0.0.0. Once a ping is attempted， it fails. Which of the following options is the most probable cause of the failed ping？（）
- A0 is not valid in an IP address
- B128 is a reserved network
- CThe subnet mask should be 255.255.0.0. since it is a class B
- DA network problem has occurred since IP and subnet are valid