Message delivery is the communication method between objects. An object request services from another object by sending messages. A message usually includes: ________

A、message-sender’sidentification,operationnameandnecessaryparameters;
B、theclassnamesofmessage-senderandmessage-receiver;
C、message-receiver’sidentification,operationnameandnecessaryparameters;
D、theclassnameofthemessage-receiver