What characterizes a period when at least one factor of production is fixed?

The period when at least one factor of production is fixed is characterized as the short run. In economic terms, the short run refers to a timeframe in which at least one input or factor of production cannot be changed or adjusted easily. This means that businesses and producers have limitations on how quickly they can respond to changes in demand or market conditions because some resources, such as labor or capital, are fixed.

In contrast, the long run involves a situation where all factors of production can be altered; businesses can fully adjust their resources in response to market demands. The other options, such as a dynamic market or a stable economy, do not directly address the flexibility of production factors within a specific timeframe. Thus, focusing on the fixed nature of at least one production factor is the defining characteristic of the short run.