• Queue as a FIFO Data Structure:
• Queue: A linear data structure operating under the FIFO (First-In, First-Out) principle, where elements are enqueued at the rear and dequeued from the front.
• Stack: Operates under the LIFO (Last-In, First-Out) principle (insertion and deletion at the same end/top).
• Linked List & Graph: Can support various access disciplines depending on pointer implementation.
• Conclusion: The FIFO data structure is Queues (Option 3).

Correct option: (3) Queues

• Fiber Optic Communication - Attenuation:
• Attenuation: The reduction or loss in optical signal power as light pulses propagate through the optical fiber core over distance, typically measured in decibels per kilometer (dB/km).
• Caused primarily by absorption (material and impurity absorption) and scattering (Rayleigh scattering).
• Other Terms:
• Propagation: The physical transmission and wave motion of light through the fiber.
• Scattering: A physical mechanism contributing to attenuation.
• Conclusion: The loss in signal power is called Attenuation (Option 1).

Correct option: (1) Attenuation

• Combinatorics - Permutation vs. Combination:
• Permutation of a set of $n$ elements is an arrangement of the elements in a specific, definite order:

• Combination is a selection of elements where the order of arrangement does not matter:

• Conclusion: An arrangement in a given order is a Permutation (Option 2).

Correct option: (2) Permutation