When the Marginal Product of Labor is negative, we are in. A. stage I for land B. stage III for labor C. stage II for land D. none of the above

When the Marginal Product of Labor is negative, we are in stage III for labor. So, the correct answer is B. stage III for labor.

Here's why:

The theory of production identifies three stages of production:

1. Stage I: Increasing returns to the variable input (labor in this case). In this stage, each additional unit of labor increases total output by a larger amount than the previous unit.

2. Stage II: Diminishing returns to the variable input. In this stage, each additional unit of labor still increases total output, but by a smaller amount than the previous unit.

3. Stage III: Negative returns to the variable input. In this stage, each additional unit of labor actually decreases total output. This is because the fixed input (land or capital) becomes over-utilized.

So, when the Marginal Product of Labor is negative, it means that adding more labor is actually reducing total output, which is characteristic of Stage III.