In the following question, choose the option that is opposite in meaning to the word "INVALUABLE".

Introduction / Context:
This vocabulary question asks for an antonym, or opposite in meaning, for the word "invaluable". Many candidates are misled because "invaluable" looks similar to "valueless", but it actually means extremely valuable or too valuable to be measured in money. Recognising this positive sense is essential before you look for an opposite. Once the correct meaning is clear, you then need to identify a word that expresses a very low or zero value, which becomes the antonym.

Given Data / Assumptions:
• Target word: invaluable. • Invaluable means extremely valuable or beyond calculable worth. • The answer choices are priceless, rare, inestimable, and worthless. • The task is to choose the word closest to the opposite meaning.

Concept / Approach:
The starting point is to correct any misunderstanding about the meaning of "invaluable". The prefix "in" in this word does not create a negative sense; instead, the word has evolved to mean "so valuable that its value cannot be measured easily". Therefore, an antonym must express the idea of having no value or very little value. Among the options, priceless and inestimable are actually synonyms or near synonyms of invaluable, while rare describes scarcity rather than value alone. The word that expresses the exact opposite is "worthless".

Step-by-Step Solution:
1. Define "invaluable" as extremely valuable or highly precious. 2. Consider "priceless", which also means extremely valuable, sometimes beyond price, so it has a similar positive meaning. 3. Consider "inestimable", which again means too great to calculate or estimate, so it is close in meaning to invaluable. 4. Consider "rare", which refers to something that is uncommon, but rarity alone does not always mean no value or strong value. 5. Consider "worthless", which means having no worth or value. 6. Recognise that since invaluable is extremely valuable, the natural opposite is "worthless".

Verification / Alternative check:
A quick test is to imagine a sentence: "Her advice was invaluable to me." If you wanted to say the opposite, you would say "Her advice was worthless to me", not "rare" or "priceless". Both priceless and inestimable would keep the same positive meaning and would not change the sense of the sentence. This replacement method confirms that worthless is the only answer that reverses the meaning correctly.

Why Other Options Are Wrong:
Option A, priceless, shares a similar meaning with invaluable and is therefore a synonym rather than an antonym. Option B, rare, only tells you how common something is and does not directly indicate great or poor value. Option C, inestimable, again means that the value cannot be calculated because it is so high, which is very close to invaluable. Since the question requires an opposite, none of these options meets the requirement. Only worthless expresses the idea of having no value at all.

Common Pitfalls:
Many learners incorrectly assume that "invaluable" must be negative because of the "in" prefix and therefore choose a positive word like priceless as the opposite. This is a good example of why memorising word meanings from real usage is better than guessing from prefixes. Another mistake is to pick rare simply because rare things are often valuable, but rarity is not the exact opposite of being extremely valuable. Always ensure that an antonym directly reverses the main idea of the original word.

Final Answer:
The word that is opposite in meaning to "invaluable" is WORTHLESS.