The correct answer is option 'A': CISC (Complex Instruction Set Computing).

Explanation:

CISC stands for Complex Instruction Set Computing. It is a type of computer architecture that is characterized by a large set of complex instructions. The IA-32 system, also known as x86, is an example of a CISC architecture.

Here are the key points that explain why the IA-32 system follows the CISC design:

1. Complex instructions: CISC architectures have a wide variety of complex instructions that can perform multiple tasks in a single instruction. The IA-32 system supports instructions that can perform arithmetic operations, logical operations, memory access, and control flow operations, among others.

2. Variable instruction length: In CISC architectures, instructions can have variable lengths. The IA-32 system supports instructions of different lengths, ranging from 1 byte to 15 bytes. This allows for more flexibility in encoding complex instructions.

3. Emphasis on hardware: CISC architectures tend to rely more on complex hardware to implement the instructions. The IA-32 system includes a wide range of specialized hardware units, such as the arithmetic logic unit (ALU), the control unit, and the memory management unit (MMU), to efficiently execute the complex instructions.

4. Memory access: CISC architectures typically have instructions that can directly access memory operands. The IA-32 system provides instructions that can load and store data from/to memory locations, making it easier to manipulate complex data structures.

5. Instruction decoding: CISC architectures require complex instruction decoding units to interpret and execute the instructions. The IA-32 system contains a microcode engine that translates the complex instructions into micro-operations, which are then executed by the hardware units.

6. Backward compatibility: CISC architectures, including the IA-32 system, often prioritize backward compatibility. This means that newer processors are designed to be able to execute software written for older processors. This allows for a smooth transition and ensures compatibility with legacy software.

In conclusion, the IA-32 system follows the CISC design, which is characterized by a large set of complex instructions, variable instruction lengths, emphasis on hardware, memory access instructions, complex instruction decoding, and backward compatibility.