Time Voyager is a feature of Juniper Apstra that allows you to restore previous revisions of a blueprint, which is a logical representation of your network design and configuration. Time Voyager automatically saves the five most recent blueprint commits, which are the changes that you apply to the network. You can also manually save up to twenty-five revisions by keeping them, which prevents them from being overwritten by new commits. Therefore, the correct answer is B and D. Time Voyager retains the five most recent blueprint commits and Time Voyager retains up to twenty-five saved revisions. References: Time Voyager | Apstra 4.1 | Juniper Networks, Time Voyager Introduction | Apstra 4.2 | Juniper Networks, Juniper Apstra at a Glance | Flyer

The Links table in the Staged tab shows the physical connections between the devices in the fabric. It provides information such as the source and destination device names, hostnames, serial numbers, roles, interfaces, and link status. The Links table can be used to assist the team that is installing and cabling the devices by verifying that the devices are connected correctly and that the links are operational. The Links table can also be used to troubleshoot any connectivity issues that may arise during the installation process. For more information, see Links (Staged). References:
* Links (Staged)
* Topology (Staged)
* Staged

Juniper Apstra provides four system-defined user roles that are available in the Apstra GUI environment. They are: administrator, device_ztp, viewer, and user1. Based on the web search results, we can infer the following statements:
* viewer: This role includes permissions to only view various elements in the Apstra system, such as blueprints, devices, design, resources, external systems, platform, and others. Users with this role cannot create, edit, or delete any element12.
* user: This role includes permissions to view and edit various elements in the Apstra system, such as blueprints, devices, design, resources, external systems, platform, and others. Users with this role cannot create or delete any element12.
* authorized: This is not a system-defined user role in Juniper Apstra. It is a term used to describe users who have been authenticated by an external system, such as LDAP, Active Directory, TACACS+, or RADIUS3.
* root: This is not a system-defined user role in Juniper Apstra. It is a term used to describe the superuser account on a Linux system, which has full access to all commands and files. Creating a user in the Apstra GUI does not provide that user access to the Apstra platform via SSH. To access the Apstra platform via SSH, you must create a local Linux system user4. References:
* User / Role Management Introduction
* User/Role Management (Platform)
* AAA Providers
* User Profile Management