Which platform is a virtual version of IOS XE Software for cloud deployments?

The Cisco CSR 1000v is a virtualized router that runs a version of IOS XE Software specifically designed for cloud environments. It provides similar functionality to the physical Cisco ISR (Integrated Services Routers), enabling features such as routing, security, and VPN services, but it operates as a software-based solution in virtualized data centers or cloud infrastructure. This flexibility allows organizations to deploy routing capabilities without the need for physical hardware, facilitating rapid scaling and efficient resource management.

The other options represent different Cisco products that do not serve as direct virtual versions of IOS XE Software. The Cisco ISR 4000 is a line of physical routers rather than a virtualized platform. The Cisco ASA 5500 series primarily focuses on security rather than providing a complete routing solution. Meanwhile, the Cisco Nexus 9000 series is a family of data center switches, designed to optimize data center environments but not specifically as a virtual IOS XE solution. Thus, the CSR 1000v stands out as the appropriate answer due to its purpose of enabling cloud-based deployments of IOS XE.