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Difficulty: HardCausal Detail Extraction

Modern transoceanic fiber-optic cables utilize protective galvanized steel armor to withstand seabed abrasion. In deep benthic environments, electrolytic reactions between the steel casing and adjacent copper conductors can generate free hydrogen gas. When ambient hydrostatic pressure forces this liberated hydrogen to diffuse through the inner polymer cladding, the gas bonds chemically with defects in the pure silica glass core. Consequently, this molecular bonding forms hydroxyl ions that absorb infrared light at standard transmission wavelengths, causing severe signal attenuation over extended distances. While mechanical strain and microbending also induce transmission losses, it is this specific chemical reaction that permanently degrades optical clarity.

According to the passage, what directly causes the formation of light-absorbing hydroxyl ions within the cable?

  1. A
    Physical microbending and mechanical strain resulting from seabed abrasion
  2. Chemical bonding between diffused hydrogen gas and defects in the silica coreAnswer
  3. C
    Severe attenuation of optical signals across extended transmission distances
  4. D
    Direct thermal degradation of the outer polymer cladding from high electrical currents

Answer

Chemical bonding between diffused hydrogen gas and defects in the silica core directly forms the light-absorbing hydroxyl ions.
The passage clearly establishes the causal chain by noting that hydrogen gas diffuses into the core and 'bonds chemically with defects in the pure silica glass core,' which '[c]onsequently... forms hydroxyl ions.' Therefore, the chemical bonding between hydrogen and core defects is the direct stated cause.

Step-by-Step Solution

1
Locate the targeted effect in the text.
Identified the mention of 'forms hydroxyl ions that absorb infrared light'.
The question asks specifically for the direct cause of hydroxyl ion formation.
2
Examine the causal signal words immediately preceding the target effect.
Found the causal transition 'Consequently, this molecular bonding forms...'
Causal conjunctions explicitly link the preceding mechanism to the resulting consequence.
3
Trace the antecedent reference of 'this molecular bonding' in the preceding sentence.
The text specifies that 'the gas bonds chemically with defects in the pure silica glass core.'
This establishes the precise factual cause directly stated by the author.

Key Concept

Causal Detail Extraction
Estimated Time:1m 20s
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Topics

Causal Detail Extraction

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