The correct answer is C. In protected mode.
In real mode, the 80286 has the same 16-bit register set as the 8086. In expanded mode, the 80286 can access an additional 16MB of memory, but the register set remains the same. In protected mode, the 80286 has a 32-bit register set, which allows it to access up to 4GB of memory.
Here is a brief explanation of each option:
- A. In real mode, the 80286 has the same 16-bit register set as the 8086. This means that it has 16 registers, each of which is 16 bits wide. The registers are used to store data and instructions.
- B. In expanded mode, the 80286 can access an additional 16MB of memory. However, the register set remains the same as in real mode. This means that the 80286 can only access 1MB of memory at a time.
- C. In protected mode, the 80286 has a 32-bit register set. This means that it has 32 registers, each of which is 32 bits wide. The registers are used to store data and instructions. Protected mode also allows the 80286 to access up to 4GB of memory.
- D. Interrupt mode is a state that the 80286 can enter when it receives an interrupt. An interrupt is a signal that tells the 80286 to stop what it is doing and execute a special routine. The register set is not changed when the 80286 enters interrupt mode.