"A table that extends another table is called a child class, and the table it extends is the parent class" - this is about halfway down in this link below: https://docs.servicenow.com/en-US/bundle/tokyo-platform-administration/page/administer/table-administration/concept/table-extension-and-classes.html

Access Controls are rules that define who can access what data and how they can access it. When configuring an Access Control, you can specify the table, operation, and role for the rule. You can also add a condition or a script to further refine the rule. If you do not add a condition or a script, the rule will apply to all records and fields on the table.
The statements A, B, and C are true for Access Controls that have no condition or script. For example:
table.* will grant access to every field in a record. This means that the user can view and edit all the fields on the record, regardless of their role or any other criteria.
table.None will grant access to every record on the table. This means that the user can view and edit all the records on the table, regardless of their role or any other criteria.
table.field will grant access to a specific field in a record. This means that the user can view and edit only that field on the record, regardless of their role or any other criteria.
The statement D is not true for Access Controls that have no condition or script. table.id will not grant access to a specific record on the table. This is because the id is not a field name, but a unique identifier for the record. To grant access to a specific record on the table, you need to add a condition or a script that matches the id of the record.
Reference:
[Access Control rules]
[Create an Access Control rule]

"Schema map: Provides a graphical representation of the relationships between tables."
https://docs.servicenow.com/bundle/tokyo-platform-administration/page/administer/table-administration/concept/c_TableAdministration.html

When evaluating Access Controls, ServiceNow searches and evaluates:
From the most specific match to the most generic match. This is the correct answer because ServiceNow follows a top-down approach when evaluating Access Control (ACL) rules, which are used to restrict the access to the data and functionality of the ServiceNow platform based on the user's roles and conditions. ServiceNow starts with the most specific match, which is the field-level ACL rule, then moves to the table-level ACL rule, and finally to the global or * ACL rule. ServiceNow grants access if any of the ACL rules evaluates to true, and denies access if all of the ACL rules evaluate to false.
The following are not correct descriptions of how ServiceNow searches and evaluates Access Controls:
Only for matches on the current table. This is not correct because ServiceNow does not only look for matches on the current table, but also on the parent tables and the global or * table. For example, if there is no ACL rule for the incident table, ServiceNow will look for an ACL rule for the task table, which is the parent table of the incident table, and then for the global or * table, which is the parent table of all tables.
Only for matches on the current field. This is not correct because ServiceNow does not only look for matches on the current field, but also on the table that contains the field and the global or * table. For example, if there is no ACL rule for the short_description field on the incident table, ServiceNow will look for an ACL rule for the incident table, and then for the global or * table.
From the most generic match to the most specific match. This is not correct because ServiceNow does not follow a bottom-up approach when evaluating Access Controls, but a top-down approach, as explained above. Reference: Access Control Rules, ACL Evaluation Order
https://developer.servicenow.com/dev.do#!/learn/learning-plans/paris/new_to_servicenow/app_store_learnv2_securingapps_paris_access_controls_evaluation_order

https://docs.servicenow.com/bundle/tokyo-application-development/page/build/applications/task/set-RCA-level.html