Option D, These countries experience diminishing returns to physical capital per worker with technology and human capital per worker being fixed
Explanation:
The curve which represents the relationship between physical capital per employee and production per employee illustrates the value of human capital per employee and technologies.
Both Albernia and Brittania have decreasing returns on physical capital as the same incremental rises in physical capital per employee in both countries — continuous job retention in human capital and technology — will lead in smaller and less actual GDP changes per employee.
So, Both human capital per worker and technology are held fixed. Yes, there are diminishing returns.