Final answer:
As countries develop economically, the share of workers in the primary or agricultural sector decreases, as seen with the shift to manufacturing and services sectors.
Step-by-step explanation:
As countries develop economically, the share of workers in the primary or agricultural sector tends to decrease. This phenomenon is due to the structural transformation that accompanies economic growth. Initially, a majority of the population is engaged in agriculture and other primary activities, primarily because these sectors offer the most employment opportunities in a developing country. However, as a country develops, it experiences a shift where labor moves from agriculture to more productive sectors, such as manufacturing and services.
With continuous development, you find economies transitioning further with the majority of the workforce moving into the service industries or the tertiary sector. This transition is evident in highly developed economies like the United States, Japan, and Western Europe. For instance, in the United States, almost 80 percent of the workforce is now employed in the service sector. Historical patterns support the claim that as economic development occurs, the share of agricultural workers declines.
Therefore, the answer to the question is 'a. The share goes down' as countries develop economically.