Idiom and phrase: what does the expression "to buy a lemon" mean?

Introduction / Context:
This question tests your knowledge of the idiom "to buy a lemon". Idioms are fixed expressions whose meanings cannot always be guessed from the individual words. This idiom is widely used, especially in contexts involving second hand cars or other expensive items that turn out to be faulty. Understanding idioms is essential for scoring well in English vocabulary and usage sections of competitive exams.

Given Data / Assumptions:

• The idiom in question is "to buy a lemon".
• The context is general English idiomatic usage, often related to purchases.
• The answer choices refer to vehicles, recipes, useful insignificant things, and unnecessary purchases.
• We assume standard modern usage of the idiom, as found in common English references.

Concept / Approach:
In modern English, especially in American usage, "a lemon" is a slang term for a car or other product that looks fine at first but has many mechanical problems or defects. Therefore, "to buy a lemon" means to buy something, typically a vehicle, that turns out to be faulty and causes repeated trouble. The idiom has nothing to do with food recipes or with buying unnecessary items in general.

Step-by-Step Solution:
Step 1: Recall or look up the standard meaning of the idiom "a lemon" in the context of purchases. Step 2: Note that the term is especially associated with defective cars that break down often or require frequent repairs. Step 3: Examine option A: it directly mentions "to purchase a vehicle that constantly gives problems", which aligns exactly with the idiomatic meaning. Step 4: Examine option B: it talks about recipes and has no connection with the idiom as used in English. Step 5: Consider option C: it suggests buying something insignificant that later becomes useful, which is almost the opposite of buying a faulty product. Step 6: Consider option D: it mentions buying unnecessary stuff, which may be wasteful but does not capture the idea of hidden defects and constant problems. Step 7: Conclude that option A is the only one that accurately reflects the idiom.

Verification / Alternative check:
You can verify this meaning by thinking of common usage contexts such as "He bought a second hand car, but it turned out to be a lemon." The sentence clearly expresses disappointment due to mechanical faults. Nothing in the typical usage suggests anything about recipes or items that later become helpful. The focus is on hidden faults and repeated breakdowns, which option A captures.

Why Other Options Are Wrong:
Option B: This is unrelated to the idiom and seems to be a distractor built around literal food imagery. Option C: Describes a lucky outcome where an insignificant item becomes very useful, which is positive, whereas buying a lemon is negative. Option D: Refers to impulsive or unnecessary shopping, which is a different idea from buying a defective product.

Common Pitfalls:
Learners sometimes misinterpret idioms literally or confuse them with similar sounding phrases. Another trap is to pick a vaguely negative option without checking that it matches the specific nuance of the idiom. For "buy a lemon", the key idea is not just a bad financial decision but a purchase that repeatedly fails due to defects. Remembering a few typical example sentences can help anchor idioms in your mind.

Final Answer:
The expression "to buy a lemon" means to purchase a vehicle that constantly gives problems, so option A is correct.