The correct answer is: B. ws-discovery
ws-discovery is a web service specification that defines a protocol for discovering web services on a local network. It is based on the Simple Service Discovery Protocol (SSDP), which is a multicast protocol.
ws-agent is a web service specification that defines a protocol for managing web services on a local network. It is based on the Web Services Distributed Management (WSDM) specification.
ws-soap is a web service specification that defines a protocol for exchanging messages between web services. It is based on the Simple Object Access Protocol (SOAP).
Therefore, the only option that is a specification for multicast discovery on a LAN is ws-discovery.