Which statement best captures the relationship between RISC and CISC in modern CPUs?

• A. RISC emphasizes complex instructions; CISC emphasizes simple instructions.
• B. Modern CPUs blend philosophies via pipelining, multiple execution units, and micro-ops; ARM (RISC) vs x86 (CISC) paradigms.
• C. ARM is CISC; x86 is RISC.
• D. Modern CPUs optimize exclusively for power efficiency and do not use pipelining.

Answer: (B)

In modern CPUs, the line between RISC and CISC has blurred. Many processors that started from a CISC idea still break instructions into simpler internal steps called micro-operations, and then schedule those micro-ops across multiple execution units in a pipelined, out-of-order core. This approach lets the processor fetch and decode complex instructions, but internally run them as a series of simpler tasks that can be executed in parallel. ARM is associated with RISC-style instruction sets, while x86 is historically CISC, yet both rely on the same performance techniques—pipelining, multiple execution units, and micro-ops—to achieve high throughput. So, the best description is that modern CPUs blend these philosophies by using pipelines, several execution units, and micro-ops, regardless of the original ISA.