Private companies attract high-skilled professionals by offering high salaries. Most professional technicians employed in private companies make 50% more money than professionals with similar skills who work in government departments. The professional technicians hired are driven more by the public's sense of responsibility than by their personal interests, otherwise the government's professional technicians may be lost to private enterprises. Which of the following assumptions is necessary for the above discussion? ? ['Government-hired professional and technical personnel have a greater sense of public responsibility than those of private enterprises.', 'Compared with private enterprises, the government does not provide professional technicians with better conditions other than salary, such as a better working environment or benefits.', 'Professional and technical personnel will measure both personal interests and public duties.', 'Professional and technical personnel working in private enterprises work much longer than professional and technical personnel working in government.']