One of the students bought a plagiarised copy of the book.

Step 1: Analyze the question We need the word that is opposite in meaning to "plagiarised" in the sentence: One of the students bought a plagiarised copy of the book.

Step 2: Explain the concept To plagiarise means to copy someone else's work and present it as your own, or to produce a copy of something without permission. A plagiarised copy is therefore a copied, imitated, or pirated version, not the real thing.

The opposite of "copied" is "original", meaning the genuine, first-made version.

Step 3: Check each option

• A. An annotated: this means having notes added. It has nothing to do with copying.
• B. A used: this means second-hand. It is not the opposite of copied, because a used book can still be genuine.
• C. An original: this means genuine and not copied. It is the direct opposite of plagiarised.
• D. A revised: this means edited or updated. It does not contrast with copying.

Step 4: Answer The correct option is C. An original.

Step 5: Tip For "opposite in meaning" questions, first define the underlined word in your own simple words (plagiarised = copied or fake), then look for the option that means the reverse (original = genuine). Also remember the related words: plagiarism = copying, originality = authentic creativity.