The assertion and reason are correct. Frictional unemployment refers to the temporary unemployment that arises when workers are in between jobs, looking for new employment opportunities. At full employment, there is little to no spare capacity in the labor market, and jobs are plentiful. As a result, workers are able to quickly find new employment, and frictional unemployment is typically low.
It is important to note that frictional unemployment is different from structural unemployment, which refers to unemployment caused by long-term changes in the economy, such as technological advancements or changes in the skills required for certain jobs. While frictional unemployment can be considered a positive form of unemployment because it reflects a dynamic and flexible labor market, structural unemployment is typically seen as a negative consequence of economic change.