The type of greeting used in a conversation depends on which of the following?
history of the relationship
context
type of conversation desired
all of the above

I'd sat the answer is 'all of the above'. Because 'history of the relationship' is important - you won't greet a person you've just met the same way you'd great your best friend. "Context' is also important, because you won't speak the same way at a gala, or at a casual meeting with your friends. "Type of the conversation desired" is also relevant, because the way you greet someone will lead the course of your conversation.