Final answer:
In January 2018, the labor force participation rate in the United States was 62.7%.
Step-by-step explanation:
In January 2018, the labor force participation rate in the United States was 62.7% (Option A). This rate represents the percentage of adults in the economy who are either employed or who are unemployed and actively seeking employment. It is calculated by dividing the number of people in the labor force by the total adult population and multiplying by 100 to obtain the percentage. By using the historical data provided, we can see that this rate has experienced a gradual decline from its peak in the late 1999 to early 2000 period.