Explanation
Public groups let you share records with a set of users defined by criteria such as role, profile, or individual users. You can use public groups as recipients for email alerts in workflow rules or process builder.
References:
https://trailhead.salesforce.com/en/content/learn/modules/administration_essentials_for_new_admins_in_lightnin

Explanation
A public group is a grouping of users, roles, roles and subordinates, or other groups that can be used to share access to records or folders. A sharing rule is a rule that grants additional access to records based on certain criteria or ownership. In this case, the administrator should create a public group for the renewals team and create a criteria based sharing rule on opportunities that grants read-only access to the group for all closed won opportunities. This way, the renewals team can see all the opportunities that are eligible for renewal while keeping the account private. References:
https://help.salesforce.com/s/articleView?id=sf.admin_sharing.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.sharing_rules.htm&type=5

Explanation
The PARENTGROUPVAL function is a formula function that returns the value of a parent group in a report.
It can be used to compare values across different groupings and show relative performance. In this case, the administrator can use this function to show the lead source effectiveness for each country by calculating the percentage of leads from each lead source divided by the total number of leads for each country. References:
https://help.salesforce.com/s/articleView?id=sf.reports_formulas_parentgroupval.htm&type=5

Explanation
A sandbox is a copy of a production org that can be used for development, testing, or training purposes.
Sandboxes allow administrators to make changes and test them without affecting the live production org. A shared sandbox is a type of sandbox that can be used by multiple users or teams to collaborate on development or testing projects. By testing changes in a shared sandbox, the AW Computing administrator team can avoid conflicts and errors when deploying changes to production. References:
https://help.salesforce.com/s/articleView?id=sf.data_sandbox.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.data_sandbox_environments.htm&type=5

Explanation
The Campaign Member option is only available for Update when using Data Import Wizard. This means that you can use Data Import Wizard to update existing campaign members with new or modified information, but you cannot use it to create new campaign members from a spreadsheet. To create new campaign members from a spreadsheet, you need to use other tools such as Data Loader, Import Wizard for Leads and Contacts, or Manage Members button on the campaign page. References:
https://help.salesforce.com/s/articleView?id=sf.campaigns_members_adding_parent.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.data_importer.htm&type=5