In Ethernet networks, what does the acronym CSMA/CD stand for?

Introduction / Context:
This question checks your recall of a fundamental Ethernet concept: the meaning of CSMA/CD. Even though modern switched full-duplex Ethernet no longer relies on collision detection, the acronym and its behavior are core exam topics and important historically for understanding shared-media networks.

Given Data / Assumptions:
- We are working with traditional Ethernet that used CSMA/CD on shared media segments.
- CSMA/CD is an access method describing how devices share the medium and detect collisions.
- The question asks for the full phrase represented by the acronym.

Concept / Approach:
CSMA/CD stands for Carrier Sense Multiple Access with Collision Detection. Each part of the phrase describes an aspect of the access method. Carrier Sense means devices listen for existing traffic before sending. Multiple Access refers to the fact that many devices share the same collision domain. Collision Detection means devices monitor the medium while transmitting and detect if a collision occurs, at which point they send a jamming signal and back off before retrying.

Step-by-Step Solution:
Step 1: Recall that CSMA/CD is a well known Ethernet access method, and the letters C, S, M, A, C, and D each correspond to words.Step 2: Match C to Carrier, S to Sense, M and A to Multiple Access, and C and D to Collision Detection.Step 3: Combine these into the standard phrase Carrier Sense Multiple Access with Collision Detection.Step 4: Verify that this phrase accurately describes listening to the medium, sharing access, and detecting collisions.Step 5: Choose the answer option that exactly matches this standard phrase.

Verification / Alternative check:
Any networking textbook, standard, or Cisco exam guide that introduces legacy Ethernet will spell out CSMA/CD as Carrier Sense Multiple Access with Collision Detection. The phrase aligns with the operational description you see in diagrams showing devices listening, transmitting, detecting collisions, and backing off. This consistent usage across sources confirms that this is the correct expansion of the acronym.

Why Other Options Are Wrong:
Options A and C replace Access with Action and use incorrect terms like Detonation, which are not used in networking. Option B uses Collisionless Delivery, which contradicts the very idea of collision detection and is not accurate for shared Ethernet. Option E invents Centralized Switching Multiple Access, which does not correspond to any standard Ethernet terminology. Only option D matches the documented and widely accepted meaning of CSMA/CD.

Common Pitfalls:
Some learners misremember the M and A as something other than Multiple Access, or think the C and D stand for Collision Domain rather than Collision Detection. Others confuse CSMA/CD with CSMA/CA, which is Collision Avoidance, used in wireless LANs. Keeping the wires-versus-air distinction in mind helps: wired Ethernet historically used collision detection, while Wi-Fi relies on collision avoidance.

Final Answer:
CSMA/CD stands for Carrier Sense Multiple Access with Collision Detection.