Which statement about 64 Bit operating systems is true?

A 64-bit operating system is designed to take advantage of the wider data bus and greater addressable memory space available in 64-bit processors. This capability allows a 64-bit operating system to run both 64-bit applications, which can utilize the full range of the system's resources, and 32-bit applications, which were more common before the widespread adoption of 64-bit computing.

This dual compatibility is facilitated by the architecture of the operating system, which includes a compatibility layer for 32-bit applications. This means that users can still run older software that hasn’t been updated to 64-bit while benefiting from the improvements and performance gains offered by 64-bit applications.

The other statements do not accurately reflect the functionality of a 64-bit operating system. For example, a 64-bit OS does not limit itself to 64-bit applications only, nor is it inherently less efficient than a 32-bit version; rather, it typically provides better performance due to its ability to utilize more memory and handle more data at once. Additionally, while some environments may allow running 32-bit applications in a virtualized context, this is not a requirement for all 32-bit software on a 64-bit OS.