Explanation
When users log in to Salesforce via the user interface, the system checks for authentication based on their profile settings and permissions. One of the settings is login hours, which specify the time range when users can log in to Salesforce based on their profile. Another setting is Two-Factor Authentication for User Interface Logins permission, which requires users to enter a verification code along with their username and password when they log in to Salesforce via the user interface. References:
https://help.salesforce.com/s/articleView?id=sf.users_profiles_loginhours.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.security_2fa_perm_ui_logins.htm&type=5

The contact hierarchy is a feature that allows users to view contacts related to an account in a hierarchical tree structure based on their role or position within the account. The contact hierarchy respects record-level access by user, meaning that users can see only those contacts that they have access to based on their profile permissions and sharing settings. The other options are incorrect because contact hierarchy is not limited to
3,000 contacts at one time (it can display up to 5,000 contacts), customizing hierarchy columns does not change the recently viewed contacts list view (it only affects how contacts are displayed in the hierarchy), and sharing settings are not ignored by contacts displayed in the contact hierarchy (they determine which contacts are visible to users). References: https://help.salesforce.com/s/articleView?id=sf.contacts_hierarchy.
htm&type=5