In the following question, choose the correct meaning of the English idiom wild goose chase.

Introduction / Context:
This question checks understanding of an English idiom. Idioms are fixed expressions whose meaning cannot always be guessed from the literal meanings of the individual words. Wild goose chase is a common idiom used in conversation, journalism, and literature. Knowing such idioms helps learners understand nuanced texts and also improves their own spoken and written English in exams and professional life.

Given Data / Assumptions:

• The idiom given is wild goose chase.
• Four possible interpretations are supplied as options.
• Only one option correctly explains how this idiom is used in standard English.
• The answer must reflect both the idea of being hopeless and the outcome being unattainable.

Concept / Approach:
Idioms often arise from vivid images. Chasing a wild goose in real life would be extremely difficult and almost impossible to complete successfully. Therefore, the idiom wild goose chase symbolises a long or complicated search that is unlikely to succeed. The key idea is not just wasting time, but specifically trying to get something that cannot realistically be obtained. Candidates must look for the option that captures this hopelessness and impossibility. Options that talk about adventure, small returns, or fun fail to express that core meaning.

Step-by-Step Solution:
Step 1: Read the idiom wild goose chase and recall if you have seen it in stories or articles. Step 2: Examine option a, a hopeless search for something unattainable. This suggests a long effort toward a goal that cannot be achieved. It closely matches the image of chasing a wild goose. Step 3: Examine option b, an adventurous trip full of surprises. Although the picture of chasing animals may look adventurous, the idiom is not normally used in a positive sense. Step 4: Examine option c, to waste a lot of time and effort for small returns. This focuses on low benefit rather than impossible success, so it is not fully accurate. Step 5: Examine option d, to have fun doing a certain task. There is no element of enjoyment in the idiom; it is usually negative. Step 6: Conclude that option a is the closest and correct meaning of the idiom.

Verification / Alternative check:
Consider a sample use: The detective realised he had been on a wild goose chase because the suspect had already left the country. In this sentence, the emphasis is on a fruitless effort that was doomed from the start. There is no sense of fun or adventure in a positive way. Another example is, Trying to find that old file in this office is a wild goose chase. Again, the focus is impossibility. These examples confirm that the idiom signifies a hopeless search for something unattainable, matching option a exactly.

Why Other Options Are Wrong:
An adventurous trip full of surprises: This suggests excitement and generally positive feelings, which are not present in the idiom.
To waste a lot of time and effort for small returns: This is closer but still not precise, because the idiom implies near impossibility rather than simply low benefit.
To have fun doing a certain task: This is entirely incorrect, since wild goose chase usually carries a frustrated tone.

Common Pitfalls:
Students sometimes misinterpret idioms by focusing only on literal images. They may imagine excitement in chasing a wild animal and pick an adventurous meaning. Another mistake is to treat the idiom as simply about wasting time, ignoring the element of an unattainable goal. The best strategy is to learn idioms through real sentences and short stories, not as isolated phrases, so that the tone and context become clear.

Final Answer:
The idiom wild goose chase means a hopeless search for something unattainable, so option a is correct.