Memory technologies — identify the semiconductor memory Which of the following choices is a semiconductor memory device used for random access storage?

Introduction / Context:
Computer memory technologies range from semiconductor-based volatile storage to optical and magnetic nonvolatile media. Distinguishing these categories is important for system architecture, performance analysis, and embedded design.

Given Data / Assumptions:

• Looking for a semiconductor memory type.
• Focus on mainstream components used as main memory or cache.

Concept / Approach:
Random Access Memory (RAM) is a semiconductor memory family (DRAM, SRAM). It provides read/write capability with fast access, typically volatile (contents lost at power-down). MAR (Memory Address Register) is a CPU register, not a memory technology. CD and CD-ROM are optical storage media, not semiconductor RAM.

Step-by-Step Solution:

Verification / Alternative check:
System block diagrams show RAM chips (DRAM DIMMs, SRAM caches) connected via memory buses; MAR appears within the CPU datapath; CDs attach via storage interfaces and have orders-of-magnitude different latency and bandwidth.

Why Other Options Are Wrong:

• MAR: Not a memory device, a processor register.
• CD-ROM / CD: Optical media, non-semiconductor, sequential/sector access.

Common Pitfalls:
Confusing memory devices with architectural registers or with storage media. RAM is volatile, whereas optical discs are nonvolatile and much slower.

Final Answer:
RAM