The correct answer is: B. Proportion of population working or looking for work.
The labor force participation rate is the percentage of the civilian noninstitutional population that is either employed or unemployed. It is calculated by dividing the labor force by the civilian noninstitutional population. The labor force includes all people who are employed and all people who are unemployed but actively looking for work. The civilian noninstitutional population includes all people who are 16 years of age or older and not institutionalized, such as in prison or a mental hospital.
Option A is incorrect because it only includes people who are working. Option C is incorrect because it only includes skilled workers. Option D is incorrect because it only includes female workers.