The opener for a sales message should be

A、provocative, humorous or entertaining, and medium length (5-10 lines).;

B、stimulating, relevant, honest, and short (1-5 lines).;

C、appealing, informative, persuasive, conversational, and medium length (5-10 lines).;

D、entertaining or serious, focused, persuasive, and short (1-5 lines).