Final answer:
The unemployment rate is the percentage of the labor force that is unemployed, including those actively seeking employment and excludes the adult population not looking for a job.
Step-by-step explanation:
The unemployment rate is defined as the percentage of people in the labor force who do not have a job. To be considered part of the labor force, individuals must be employed or actively seeking employment. Therefore, the correct answer to the question is a) the percentage of the Labor Force that is unemployed. It's important to understand that the unemployment rate does not include the entire adult population, but rather focuses on those who are without a job and are searching for one. People who are without a job and not looking for one are classified as 'out of the labor force' and are not part of the unemployment rate calculation.