Read the following passage and answer the item that follows. Your answer to this item should be based on the passage only.

Counting the unemployed sounds simple until the definitions are examined closely. A worker who has stopped actively searching for work after months of rejection is, by most official definitions, no longer counted as unemployed at all, even though their circumstances have not improved. Someone working one hour a week out of financial desperation counts, in many national statistics, as employed. And a single national unemployment rate can conceal sharply different realities between a country's cities and its remote regions, or between its formally registered workforce and the far larger share working informally, entirely outside any register.

Why is the standard unemployment rate, on its own, only one measure of the underlying problem of joblessness?