Knowledge marketing: through effective knowledge dissemination methods and channels, the company's valuable knowledge (including product knowledge, professional research results, business ideas, management ideas and excellent corporate culture) owned by the company is passed to potential users, and gradually Forming awareness of corporate brands and products for the process of ultimately converting potential users into users and various marketing behaviors. Which of the following behaviors belong to knowledge marketing:. ['A public hospital sent 10 senior doctors to participate in community volunteer medical volunteer activities.', 'A securities company organizes a retired elderly class to explain the stock market knowledge for free.', 'A famous brand company anonymously donated 10 million yuan for the hope project.', 'Liu, who works in a pharmaceutical factory, often discusses with his friends about diet health.']