To create an environment variable that can be used by several policies in the Embedded Event Manager, the engineer should use the command N9k2 (config)# event manager environment mailserver ''10.10.10.10''. This command defines a global environment variable named mailserver with the value of 10.10.10.10, which represents the external email server. The environment variable can then be referenced by any policy that needs to use the email server in its actions, such as sending notifications or alerts. The environment variable can also be modified or deleted as needed. The other commands are incorrect because they either use the wrong mode, the wrong keyword, or the wrong syntax. References := * Implementing and Operating Cisco Data Center Core Technologies (DCCOR) v1.2, Module 3: Data Center LAN Network Connectivity, Lesson 3.4: Cisco Nexus 9000 Series Switches * Cisco Nexus 9000 Series NX-OS System Management Configuration Guide, Release 9.3(x), Chapter: Configuring Embedded Event Manager