What is the purpose of the training models within Oracle Digital Assistant?

Considerthis codesnippet:

Whichtwostatementsaboutthis codearetrue?

want to save some user input, such as the type of pizzaa particular user last ordered, so that it's available the next time that user starts a conversation.
Which type of variable should you use to persist values across multiple invocations of the conversation?

Which variable type is automatically set with values from the chat client,such aslocate and timezoneoffset?

As per Oracle's recommendation,which is the best practice regarding conversational design?