In the long run, which of the following is true about all inputs in the production process?

• A. Inputs cannot be changed.
• B. All inputs are fixed.
• C. All inputs are variable.
• D. Some inputs are fixed and some are variable.

Answer: (C)

Verified step by step guidance

1. Understand the difference between short-run and long-run in production theory: In the short run, at least one input is fixed, while in the long run, firms can adjust all inputs.
2. Recall the definition of fixed and variable inputs: Fixed inputs cannot be changed in the short run, whereas variable inputs can be adjusted depending on the level of output.
3. Recognize that the long run is a planning horizon where firms have the flexibility to change all factors of production, including capital, labor, and other inputs.
4. Conclude that since firms can adjust all inputs in the long run, no input remains fixed; therefore, all inputs are variable in the long run.
5. Hence, the correct statement is: 'All inputs are variable' in the long run.