Select the most appropriate ANTONYM of the highlighted word in the given…

Concept

An antonym is a word that expresses a meaning opposite to that of a given word. To find the antonym of a word used in a sentence, first fix its meaning in that exact context, then choose the option whose meaning stands in direct opposition to it.

Application

In the sentence, “redundant” describes background material that is not needed — that is, unnecessary, superfluous, more than what is required. The word carrying the opposite meaning — something that IS needed or required — is “Essential”, which means absolutely necessary or fundamentally required.

Contrast

• “Verbose” means using more words than necessary, wordy — this sense is actually close to “redundant” (both relate to excess), so it functions as a near-synonym rather than an opposite.

• “Humorous” means intended to cause amusement — a quality unrelated to necessity or excess, so it does not oppose “redundant” in meaning.

• “Inflexible” means rigid or unable to adapt — again unrelated to whether something is needed or excessive.

Since “Essential” is the direct semantic opposite of “redundant” in this context, it is the correct antonym.