Choose the option that is most nearly opposite in meaning to the underlined word and that will correctly fill…

Analyze the question

The underlined word is "trivial" (the word appears in the sentence, though the underline isn't visible here). We need a word that:

1. Is opposite in meaning to "trivial", and
2. Fits the gap in the sentence logically.

Explain the concept

"Trivial" means of little importance or value; insignificant. Its antonyms include serious, important, significant, grave, major.

Test each option

• A. serious: This is a direct opposite of "trivial" (unimportant vs. serious/significant). It fits the sentence: "A trivial issue often becomes serious when it is not properly handled." ✔
• B. valuable: It suggests worth, but it doesn't fit the meaning of an issue that grows worse when mishandled. ✘
• C. ordinary: It is closer to a synonym of "trivial" (common, unremarkable). ✘
• D. unbearable: It means too severe to endure. It fits the sentence somewhat, but it is too extreme and is not the true opposite of "trivial". The natural antonym is "serious". ✘

Answer

The best option is A. serious.

Tip: In "opposite meaning" questions that also require a gap fill, first find the standard antonym of the key word, then check that it reads naturally in the sentence. Beware of options like "unbearable" that fit the context but are too extreme to be the exact opposite.