Out of the four given words, two of them are either synonyms or antonyms of each other. Identify the correct pair.
Here we are given four words, Prolixity, Brevity, Agreement, and Proposition, and we need to spot the pair that shares a synonym or antonym relationship.
Looking across the four words, only Prolixity and Brevity connect to the same underlying idea, the length of speech or writing, but from opposite directions. One means talking too much, the other means saying just enough. Agreement and Proposition both belong to a different area of meaning entirely, dealing with consent and suggestions rather than length of expression, so neither pairs cleanly with Prolixity or Brevity, nor with each other in a strict synonym or antonym sense.
Let's summarize:
The correct pair is Prolixity and Brevity, so the answer is option (a), I and II.