Topic: Root, Prefix, Suffix, Affix, Infix, Morpheme & Derivatives,

Best Answer Explained in Below-:

To understand why "un" is the correct prefix to create the opposite of the word "certain," we first need to examine the meaning of "certain." The term "certain" conveys a sense of assurance, confidence, or definiteness about something. To find its antonym, we want a prefix that denotes negation or lack of certainty.

Let's analyze the options:

A) **in** - This prefix is typically used to form adjectives meaning "not" or "opposite," like "incomplete." However, it doesn't commonly transform "certain" into a word that effectively conveys the idea of being unsure.

B) **dis** - The prefix "dis" signifies negation or reversal, as seen in words like "disagree." However, it is not commonly applied to the adjective "certain."

C) **un** - This prefix means "not" and is widely used to negate adjectives, resulting in words like "uncertain." "Uncertain" directly communicates a lack of certainty, making it the appropriate antonym.

D) **non** - This prefix signifies absence or exclusion but is less common when negating qualities in adjectives.

Thus, "un" is the most fitting choice, transforming "certain" into "uncertain," accurately capturing the opposite meaning.