English Vocabulary — Antonym (choose the word opposite in meaning to the highlighted word). Sentence (corrected): It is one of the pernicious customs prevailing in society.

Introduction / Context:
“Pernicious” is formal vocabulary often found in essays and editorials, meaning “highly harmful” or “destructive.” The sentence evaluates a social custom negatively. The antonym must therefore signal the opposite evaluative judgment: something good or helpful rather than harmful.

Given Data / Assumptions:

• Target adjective: pernicious = harmful, injurious.
• Domain: social customs and their effects.
• Options: permanent, beneficial, parochial, dangerous.

Concept / Approach:
We must reverse harmfulness. “Beneficial” means producing good results; hence it directly counters “pernicious.” Do not be distracted by look-alikes or contextually close words. “Permanent” concerns duration, not valence; “parochial” means narrow or provincial; “dangerous” is a near-synonym of harmful, not an opposite.

Step-by-Step Solution:

Verification / Alternative check:
Paraphrase: “one of the beneficial customs” directly flips the stance and remains idiomatic. The sentence still reads naturally with this replacement, confirming it as the correct antonymic counterpart.

Why Other Options Are Wrong:

• permanent: Duration, not goodness/badness.
• parochial: Narrow in outlook; unrelated to harmfulness.
• dangerous: Synonymous with harmful; not an antonym.

Common Pitfalls:
Choosing “permanent” because it contrasts superficially (temporary vs. permanent). Antonym tasks demand reversal along the concept actually tested—in this case, effect/valence, not time.

Final Answer:
beneficial