Which of the following types of RAM is most likely used in data centers and...

Data centers and high-performance servers prioritize stability and fault tolerance. CompTIA A+ identifies ECC (Error-Correcting Code) RAM as the standard memory used in such environments. ECC RAM automatically detects and corrects single-bit memory errors, preventing system crashes, data corruption, and downtime—critical requirements for servers running mission-critical workloads.

ECC memory is commonly paired with registered/buffered modules (RDIMM) for additional stability, but ECC itself is the defining feature required in data center environments. Non-ECC, unbuffered memory is used in consumer desktops where minor memory errors pose minimal risk.

Single-channel memory (B) is simply a configuration and does not imply reliability. Unbuffered RAM (C) is not used in enterprise-grade systems because it lacks error correction and electrical stabilization. RDIMM (D) includes buffering but may come with or without ECC; however, ECC is the key requirement highlighted by the question.

Therefore, the correct answer is ECC RAM.