Explanation
Excluded Resources are used to prevent certain service resources from being assigned to specific accounts or locations based on customer feedback or preferences. Assigning the Technician to a new Service Territory would affect all their service appointments, not just those for that Customer. Removing the Technician as a Preferred Resource would not prevent them from being assigned to that Customer, but would lower their priority. Creating a new Work Order Validation Rule would not affect the scheduling or optimization of service appointments, but would only validate data entry on work orders. References:
https://help.salesforce.com/s/articleView?id=sf.fs_excluded_resources.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.fs_territories.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.fs_preferred_resources.htm&type=5

Explanation
Assets are used to track the customer's install base, such as products or equipment that require service. Work orders are used to track the work that needs to be done on assets. By relating work orders to assets, the system can track the work history and status of each asset.
References: https://help.salesforce.com/s/articleView?id=sf.fsl_assets.htm&type=5

Explanation
Lightning Components are reusable units of user interface that can be customized and embedded in different pages or apps[180]. Work Order Line Items are records that track specific tasks or products related to a work order[181]. Creating a custom Lightning Component that displays Work Order progress and deploying it to Technicians through the Salesforce Field Service mobile app would allow Universal Containers' Technicians to view work progress through the Work Order Line Item card in the Salesforce Field Service mobile app by creating a component that shows the status or completion percentage of work order line items and adding it to the work order line item card layout in the mobile app settings[182]. Creating a custom Visualforce page and adding an external link in the Salesforce Field Service mobile app to view the page in the mobile browser would not allow Technicians to view work progress through the Work Order Line Item card in the Salesforce Field Service mobile app. Visualforce pages are web pages that can display custom user interface using HTML, CSS, JavaScript, and Apex[183]. Creating a Report Chart that summarizes Work Order Line Items and adding a link to the Service Appointment layout would not allow Technicians to view work progress through the Work Order Line Item card in the Salesforce Field Service mobile app. Report Charts are visual representations of report data that can be added to different pages or layouts[184]. Adding the Work Order Line Items related list to the Work Order page layout and assigning the layout to the Technician's profile would not allow Technicians to view work progress through the Work Order Line Item card in the Salesforce Field Service mobile app. Related lists are lists of records that are directly related to another record and can be added to different page layouts[185]. References:
https://developer.salesforce.com/docs/component-library/overview/components
https://help.salesforce.com/s/articleView?id=sf.fs_work_order_line_items.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.fs_mobile_custom_cards_overview.htm&type=5
https://developer.salesforce.com/docs/atlas.en-us.pages.meta/pages/pages_intro_what_is_it.htm
https://help.salesforce.com/s/articleView?id=sf.reports_charts_adding_to_layouts.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.customize_related_lists.htm&type=5