Professionalism is about the formal education and improvement level of employees. The need for long-term education and improvement implies a high level of professionalism, which is measured by the average study periods of employees. For example, medical doctors in the healthcare sector can be said to have a higher level of education, while the level of professionalism in the construction industry is less high. Likewise, lawyers in the justice sector are said to have a higher level of education, while the level of professionalism in the other occupations listed in the question is less high. Therefore, choice (b) is the correct answer.