An analyst does research about total, marginal and average product curve of labor. As more labor is hired, which of the following curves initially increases and then decreases

A. The average product of labor curve, but not the total and marginal product of labor curve.
B. The marginal product of labor curve, but not the total and average product of labor curve.
C. Both the marginal product of labor and the average product of labor curve, but not the total product of labor curve.

职业道德建设就是为建立和发展社会主义市场经济伦理秩序和伦理环境服务，为经济发展提供道德支持和精神动力。