Final answer:
Chain stores are typically referred to as operations having 10 or more units in the context of business and retail operations.
The correct option is 3.
Step-by-step explanation:
In the context of the provided text, the authors refer to chain stores as operations having 10 or more units. This is derived from the information that typically, a chain is considered to have a significant number of units, distinguishing it from single-unit operations or very small chains.
As the question proposes a range of numbers, the choice of 10 units is a commonly accepted starting point for what is considered a chain in the context of business and retail operations.
The correct option is 3.