The correct answer is: B. NuBus.
NuBus is a 32-bit expansion bus developed by Western Digital for the Apple Macintosh computer family. It was introduced in 1988 with the Macintosh II and was the standard expansion bus for Macintosh computers until the introduction of PCI in 1994.
ISA, EISA, and MCA are all 32-bit expansion buses that were developed for IBM PC-compatible computers. PCI is a 32-bit expansion bus that was developed by Intel and is the standard expansion bus for most personal computers today.
NuBus was a significant improvement over the ISA bus that was used in earlier Macintosh computers. It offered higher bandwidth, more expansion slots, and better support for graphics and other high-performance devices. NuBus was also a more open bus than ISA, which allowed for more flexibility in choosing expansion cards.
However, NuBus was also more expensive than ISA, and it was not as widely adopted by other manufacturers. As a result, PCI eventually replaced NuBus as the standard expansion bus for Macintosh computers.
Despite its relatively short lifespan, NuBus was a significant innovation in the development of personal computers. It helped to improve the performance and flexibility of Macintosh computers, and it paved the way for the development of PCI and other modern expansion buses.