Answer :
Final answer:
The number of effective workers takes into account the number of workers and their efficiency, which relates to overall labor productivity and is influenced by human capital.
Explanation:
The number of effective workers in an economy takes into account the number of workers and the efficiency of each worker. This concept is closely related to the notion of labor productivity, which accounts for the human capital possessed by workers - including education, knowledge, skills, and experience - as well as physical capital and technology. By improving the efficiency and productivity of workers, an economy can grow and develop more robustly.
To directly answer the student's question, the number of effective workers considers the efficiency of each worker (option c). This is because the efficiency of each worker can greatly impact overall labor productivity, making it a critical factor in assessing the effectiveness of a workforce.