Which of the following processors execute its instruction in a single cycle?

The correct answer is D. MIPS R2000.

The 8086 and 8088 are both 16-bit microprocessors that were introduced by Intel in 1978. They are the first processors in the x86 family of processors. The 8086 has a 16-bit data bus and a 20-bit address bus, while the 8088 has an 8-bit data bus and a 20-bit address bus. The 8087 is a 16-bit floating-point coprocessor that was introduced by Intel in 1980. It is designed to work with the 8086 and 8088 processors. The MIPS R2000 is a 32-bit RISC microprocessor that was introduced by MIPS Technologies in 1985. It is the first processor in the MIPS architecture family. The MIPS R2000 has a 32-bit data bus and a 32-bit address bus. It is capable of executing instructions in a single cycle.

The 8086 and 8088 processors are not capable of executing instructions in a single cycle. The 8087 floating-point coprocessor can execute some instructions in a single cycle, but it is not a general-purpose processor. The MIPS R2000 is the only processor in the list that is capable of executing instructions in a single cycle.