The unemployment rate is the number of people classified as unemployed as a percentage of

A) the labor force.
B) the healthy,not institutionalized population between the ages of 16 and 65.
C) the population over the age of 16.
D) the civilian population over the age of 16 who are actively employeD.

The unemployment rate is calculated as the number of individuals who are without work but actively seeking and available for employment, divided by the total number of individuals in the labor force (i.e. those who are either employed or actively seeking employment). Therefore, the correct choice is A, as it defines the labor force which is used in the calculation of the unemployment rate. The other options are either too narrow (B and D) or too broad (C) and include individuals who are not relevant to the labor force or job market.