**Rule: Understanding Idiomatic Expressions.** The idiom 'to have a bone to pick with someone' means to have a reason to be annoyed with them and to want to confront them about it. A dispute over work credit is a common cause for such a grievance. Option (b) is the correct definition. Option (a) and (d) are literal misinterpretations. Option (c) is the opposite of having a complaint.

**Rule: Understanding Idiomatic Expressions.** The phrase 'in a shambles' means to be in a state of complete mess or disarray. The fact that the company is 'on the brink of collapse' confirms this state of disorder. Option (a) is the correct definition. Option (b) and (d) are the opposite. Option (c) is a literal misinterpretation.

**Rule: Understanding Idiomatic Expressions.** The idiom 'square the circle' refers to trying to do something that is impossible. It comes from the classical geometry problem of constructing a square with the same area as a given circle using only a finite number of steps with a compass and straightedge, which has been proven impossible. Option (c) is the correct definition. Option (a) and (b) are incorrect. Option (d) is related to the origin but not the figurative meaning.

**Rule: Understanding Idiomatic Expressions.** The idiom 'until the cows come home' means for a very long time, seemingly forever. It's a rustic expression that emphasizes a long, fruitless wait. Option (a) is the correct definition. Option (b) is too specific. Option (c) is the opposite. Option (d) is an unrelated location.

**Rule: Understanding Idiomatic Expressions.** The word 'green' is often used idiomatically to describe someone who is new to a situation and therefore lacks experience. The fact that the intern is a 'fast learner' implies she is starting from a position of inexperience. Option (c) is the correct definition. Option (a) is a literal interpretation. Option (b) is the opposite. Option (d) relates to 'green-eyed monster' (jealousy), a different idiom.

**Rule: Understanding Idiomatic Expressions.** The idiom 'spill the beans' means to disclose a secret or reveal information that was supposed to be kept private. The context of a 'surprise' party makes it clear that a secret was let out. Option (c) is the correct definition. Option (a) and (d) are literal misinterpretations. Option (b) is the opposite.

**Rule: Understanding Idiomatic Expressions.** The idiom 'play it by ear' means to deal with a situation as it develops, rather than following a pre-arranged plan. When a strategy's success is uncertain, improvisation is often necessary. Option (c) correctly defines this approach. Option (a) is a literal misinterpretation. Option (b) is the opposite. Option (d) is unrelated.

**Rule: Understanding Idiomatic Expressions.** The idiom 'read between the lines' means to infer a meaning that is not explicitly stated. A detective would use this skill to understand that a suspect is being deceptive. Option (b) is the correct definition. Option (a) and (d) are literal misinterpretations. Option (c) is the opposite.

**Rule: Understanding Idiomatic Expressions.** The idiom 'skating on thin ice' means to be in a precarious or dangerous situation. Submitting a report late to a boss is a risky action that could lead to negative consequences. Option (b) correctly defines this risk. Option (a) is a literal interpretation. Option (c) and (d) are the opposite of the idiom's meaning.

**Rule: Understanding Idiomatic Expressions.** The idiom 'a flash in the pan' refers to something that has a sudden, brilliant, but short-lived success and is not repeated. The context of being 'hugely popular for a month and then disappeared' perfectly illustrates this meaning. Option (a) is the correct definition. Option (b) is the opposite. Option (c) is a literal misinterpretation. Option (d) is incorrect as the idiom implies a brief period of success before failure.