Blue Ocean strategy: refers to crossing the existing competition boundary, shifting the focus to buyer demand, screening and reordering the buyer's value elements in different markets, and changing from a positioning choice under a given structure to changing the market structure itself. which of the following are blue ocean strategies? ['An enterprise integrates innovation and utility, price and cost, and compares with the best practices of existing industries to catch up with competitors. It aims at "high-end" or "low-end" customers in the existing market, and market segments meet customer preferences.', 'A circus has turned from a child audience of traditional circus to adults and business people, expressing the plot of the theater in the form of a circus, attracting people to enjoy this unprecedented entertainment with a ticket several times higher than the traditional circus.', 'An enterprise faced the current situation of turbid water and poor nutrition in the industry circle, and decided to build its own "shark prevention net". Everyone participates in market competition and strives to "stand up chicken flocks" within one year.', 'An enterprise attaches great importance to the existing competition in the market space, and competes for a price reduction in sales. Although it has increased the cost of sales or reduced profits, it has achieved efficiency.']