The correct answer is D. State of inputs.
A production function is a mathematical relationship that shows the maximum amount of output that can be produced from a given amount of inputs, given the state of technology. The inputs are typically labor, capital, and land. The state of technology refers to the level of knowledge and expertise that is available to producers.
The state of inputs is not an attribute of a production function because it is not a factor that affects the maximum amount of output that can be produced from a given amount of inputs. The state of inputs can affect the cost of production, but it does not affect the maximum amount of output that can be produced.
For example, if a producer has access to more capital, it will be able to produce more output. However, the maximum amount of output that can be produced from a given amount of capital is still determined by the state of technology.
In conclusion, the state of inputs is not an attribute of a production function because it is not a factor that affects the maximum amount of output that can be produced from a given amount of inputs.