Select the most appropriate option that can substitute the underlined words in…

Concept: In a substitution question the replacement must match the underlined expression on two counts at once — it must carry the same meaning, and it must fit the same grammatical slot. The phrasal verb wipe out means to erase or destroy something so thoroughly that no trace of it survives, and here it stands in a past-participle slot: "half ___ in the memories of the aged."

Application: The sentence describes an answer that survives only in old diaries and has been partly erased from what old people still remember. The verb obliterate comes from the Latin obliterare, "to blot out, to strike off a written record", and means to remove something completely so that nothing of it is left — it is used precisely of writing, records and recollections being effaced. Its past participle obliterated slots straight into the sentence: "half obliterated in the memories of the aged", which reads with the same sense and the same grammar as the original.

Contrast: The other verbs belong to different meaning families, so none of them can carry the sense of erasure:

• breached — to break through a barrier or to violate an agreement, as when a dam is breached or a contract is breached; it is about breaking or violating, not about effacing.

• abided — to remain or endure, and in the fixed form abide by to comply with a rule or decision; it is about lasting or obeying, which runs opposite to being erased.

• discriminated — to perceive a difference between two things, or to treat a person unfairly on the basis of a category such as sex, caste or age; it is about distinguishing, not about removing.

Result: "Obliterated" is the substitution that preserves both the meaning of "wiped out" and its past-participle form, so the sentence becomes: "The answer lies at present locked in old diaries, half obliterated in the memories of the aged."