The main purpose of establishing a social security system is to better reflect the principle of fairness. However, there is a contradiction between fairness and efficiency. Fairness can only be relative. Especially for a developing country like China, the level of economic development is still relatively low The development of productivity and efficiency should be given priority. Only when productivity and productivity are improved can we achieve better social equity. What is the main point supported by this passage? ['Productivity determines the degree to which the principle of social equity is achieved.', 'Fairness can only be relative in any country.', "China's level of economic development is low and one-sided pursuit of fairness.", 'As long as the level of economic development is not up, social equity cannot be achieved.']