Final answer:
You should know what route you plan to take and identify alternate routes before you depart to ensure you have backup options in case of disruptions on the primary route. Alternate routes are part of the quantification process, which looks at available paths and their changes over time.
Step-by-step explanation:
When planning a trip, it's important to know what route you plan to take and identify alternate routes before you depart. This ensures that you have a backup plan in case the primary route is not accessible. Additionally, by considering alternate routes, you can assess and quantify the available options, potentially finding a path that is more efficient or scenic. This methodology falls under the concept of quantification of routes, which involves assessing the number of well-resolved geographic paths to a specific region and observing changes over time. While map grids can also be useful in navigation, they are not mentioned in this context. Therefore, the correct answer is 'B. alternate routes' because it is crucial to have a backup plan in cases where the primary route might be disrupted.