In the following question, out of the four alternatives, select the alternative which best expresses the meaning of the idiom / phrase "cock and bull story".

Introduction / Context:
The idiom "cock and bull story" is widely used in English to criticise an explanation or excuse that sounds unbelievable, overly elaborate, or clearly invented. Exams frequently test this phrase because it appears in newspapers, detective stories, and everyday conversation. Knowing its meaning helps you quickly judge the speaker's attitude toward what is being said.

Given Data / Assumptions:

The idiom under test is: cock and bull story.
We assume a conversational or narrative context where someone is describing another person's explanation.
The correct meaning should contain the idea of an incredible, fabricated, or ridiculous story, not a genuine one.
The options include references to fairy tales, animal stories, morals, bravery, and implausible excuses.

Concept / Approach:
The phrase "cock and bull story" refers to a highly unlikely story, usually invented on the spot to cover up the truth, provide a false excuse, or dramatise events. It is not a compliment; it suggests the listener does not believe the story. The key ideas are implausibility and use as an explanation or excuse. Therefore, the correct answer must capture both the lack of credibility and the purpose of the story.

Step-by-Step Solution:
Step 1: Recall typical usage: "When I asked him why he was late, he told me some cock and bull story about being kidnapped by aliens." Step 2: Identify the main features: the story is unrealistic, seems made up, and is used as an excuse. Step 3: Compare with option A: "An implausible story used as an explanation or excuse." This matches the idiom's meaning exactly. Step 4: Option B: "A fairy tale told down generations." describes traditional stories, which may be unrealistic but are not usually called cock and bull stories; they are accepted as tales, not excuses. Step 5: Option C: "A story of animals with hidden morals." is closer to fables like those of Aesop, which teach lessons and are not what this idiom refers to. Step 6: Option D: "The meek can defeat the bully by being clever" is a moral statement, not a definition of the idiom. Step 7: Option E: "A true story narrated in a humorous way." directly contradicts the false and unbelievable nature implied by the idiom.

Verification / Alternative check:
Try using each suggested meaning in a sentence. If we substitute option A, we get: "He gave me an implausible story used as an explanation or excuse." This fits well with how the idiom is used. If we substitute option B, saying "He gave me a fairy tale told down generations," the meaning weakens and does not focus on the speaker's disbelief. Option E would imply the story is true, which clashes with the normal negative tone when someone dismisses an explanation as a cock and bull story. These tests confirm that option A is the most accurate and widely accepted interpretation.

Why Other Options Are Wrong:
Option B mixes up fairy tales with excuses; "cock and bull story" is not used for folk tales told to children for entertainment.
Option C narrows the idea to animal stories with morals, confusing the idiom with fables, which are not necessarily excuses.
Option D is a moral message, possibly from a fable, but it is not a definition of the idiom at all.
Option E introduces the idea of a true story, which clashes with the core suggestion that the story is unbelievable or made up.

Common Pitfalls:
Because the words cock and bull suggest animals, some learners mistakenly associate the idiom with animal-based moral stories. However, idioms often cannot be understood literally. A good strategy is to remember typical contexts: we use "cock and bull story" when we do not believe someone's explanation. Linking the expression to disbelief and excuse, rather than to animals or morals, will help you choose the right answer in the exam.

Final Answer:
The idiom "cock and bull story" means "an implausible story used as an explanation or excuse".