Which factor characterizes unemployment?

The defining characteristic of unemployment is actively looking for a job but being unable to find one. This means that individuals who are unemployed are not currently working and are making efforts to secure employment. The essence of unemployment includes those who are part of the labor force, meaning they are available for work and have sought out job opportunities, yet have not been successful in obtaining a position.

In contrast, the other options describe situations that do not fit the formal definition of unemployment. Those who have a job but are seeking a different one are considered employed, even if they are dissatisfied. Individuals in temporary positions are also classified as employed, regardless of the nature of their employment. Lastly, those working part-time while seeking full-time work remain within the employed category, as they are currently engaged in work, albeit not to their desired capacity. Thus, option B accurately describes the condition of unemployment by focusing on the search for work without successfully securing a job.