Final answer:
The period in which a firm can change the amount of all inputs used in production is known as long-run production, allowing for adjustments in both fixed and variable inputs.
Step-by-step explanation:
The production period lengthy enough to change the amount of all inputs used in production is referred to as long-run production. During the short-run production period, a firm is able to change the amount of variable inputs, such as labor, but cannot adjust fixed inputs like capital. However, the long-run is characterized by the firm's ability to adjust all factors of production, including both fixed and variable inputs. This period duration varies depending on the specific business but is technically defined by the flexibility of altering all production inputs.