Which command is used to add "User1" to an investigation from the War Room in Cortex XSOAR?

In Cortex XSOAR, adding a user to an investigation from the War Room typically involves using an @mention format. This allows for direct tagging of users within conversations, facilitating communication and collaboration. When you use @User1, the system recognizes the command as a directive to include "User1" in the ongoing discussion, effectively notifying them and adding them to the context of the investigation.

Using this format ensures that relevant users are actively engaged in the task at hand, enhancing the workflow and enabling quicker responses. This method is widely adopted in many collaboration tools, emphasizing user engagement and interaction through simple and intuitive commands.

The other choices do not align with the established command structure for adding users in this context, which is why they are not considered correct selections.