A. PowerShell only.
Just Enough Administration (JEA) is a security technology that enables delegated administration for anything that can be managed with PowerShell. By using JEA, you can delegate specific tasks to non-administrative users without providing them full administrator rights.
Therefore, to perform remote administration tasks on Server1 by using only JEA, you should use PowerShell. Other tools like Remote Server Administration Tools (RSAT) or Remote Desktop are not necessary in this context. They provide broader administrative capabilities and are not limited to the specific roles and tasks that can be defined with JEA. So, the use of PowerShell aligns with the principle of least privilege, which is a key security benefit of JEA.