What are the main contents of the“two musts”? （ ）. A: We must ensure that the comrades continue to serve the people wholeheartedly. B: We must ensure that the comrades continue to be humble, cautious, non-arrogant and patient. C: We must ensure that the comrades continue to work hard. D: We must ensure that the comrades continue to emancipate the mind and seek truth from facts.