Which of the following architectures is supported by Ubuntu?

The correct answer is that Ubuntu supports multiple architectures, including amd64 (which is synonymous with x86_64 or x64) and UltraSPARC. The amd64 architecture pertains to the 64-bit variant of the x86 architecture, which is widely used in desktops and servers. On the other hand, UltraSPARC represents a specific instruction set architecture (ISA) designed by Sun Microsystems for its SPARC microprocessors, which is also supported by some iterations of Ubuntu, particularly for server and specialized applications.

Ubuntu's versatility in supporting different hardware architectures allows it to be used across a range of platforms, catering to diverse user needs. This capability makes it accessible not only for typical consumer-grade hardware but also for specialized computing environments, such as those found in enterprise settings or academic institutions.