Which of the following are examples of bounded (guided) transmission media used to carry signals along a defined physical path?

Introduction / Context:
Physical communication media are broadly categorized as bounded (guided) or unbounded (unguided). Bounded media confine electromagnetic energy to a physical path, while unbounded media radiate through free space. Recognizing common examples of guided media is fundamental for selecting cabling and planning link budgets. This question asks you to identify which listed items qualify as bounded media.

Given Data / Assumptions:

• We consider typical guided media used in networking and microwave links.
• Bounded media should constrain propagation within a physical structure.
• Each option is evaluated for whether it guides energy along a defined path.

Concept / Approach:
Coaxial cable guides signals between an inner conductor and shield with controlled impedance. Waveguides (rectangular or circular) confine microwave energy within conducting walls, supporting discrete propagation modes across set frequency bands. Fiber-optic cable guides light through total internal reflection in a glass core surrounded by cladding. All three are classic examples of bounded media. Therefore, the correct choice is “All of the above.”

Step-by-Step Solution:

Verification / Alternative check:
Standards and textbooks group twisted pair, coaxial cable, optical fiber, and waveguides under guided media, in contrast to radio, microwave, and infrared free-space links as unguided media.

Why Other Options Are Wrong:

• Each single item alone is a subset; the comprehensive correct answer is all listed items.
• None of the above is incorrect because all listed examples are guided media.

Common Pitfalls:
Misclassifying waveguides as “antennas” rather than as guided structures; forgetting that fiber is also bounded even though it uses light instead of electrical currents.

Final Answer:
All of the above.