The labor-force participation rate tells us the fraction of the population that

- Has chosen to participate in the labor market.

Explanation:

Labor-force participation rate is demonstrated as the segment of total population ranging between the age-group of 16 and 64 years of age (adult population) that is working actively or is in search of a job. Thus, it is basically described as the percentage of people in the economy that available for work. Therefore, it is represented as the fraction or section of people that 'has opted to participate in the labor market' and contribute to nation's economy.