Final answer:
The correct answer is A. Variability. Assuming that capacity exceeding demand is enough to ensure queues don't form ignores variability. It is important to consider variability in demand when planning capacity to avoid queues or waiting times.
Step-by-step explanation:
The correct answer is A. Variability. Assuming that capacity exceeding demand is enough to ensure queues don't form ignores variability. Variability refers to the fluctuations or differences in demand over time or across different customers. Even if capacity exceeds current demand, there may still be times when demand exceeds capacity, leading to queues or waiting times.
For example, a restaurant may have enough seating capacity to accommodate all customers on a normal day. However, during a holiday or special event, the demand for tables may exceed the restaurant's capacity, resulting in queues or waiting times.
Therefore, it is important to consider variability in demand when planning capacity to avoid queues or waiting times.