**Rule: Understanding Idiomatic Expressions.** The idiom 'make a clean sweep' has a few meanings, but in this context, it refers to getting rid of old staff or methods to make a fresh start. Hiring a 'whole new team' is a clear example of this radical change. Option (b) is the correct definition for this context. Option (a) is a literal meaning. Option (c) is another meaning of the idiom, usually in sports. Option (d) is the opposite.

**Rule: Understanding Idiomatic Expressions.** The term 'one-hit wonder' refers to a musical artist or group that is famous for only one successful song. The fact that 'they never had another popular song' is the definition of a one-hit wonder. Option (a) is the correct meaning. Option (b) is a possible part of the story, but not the full meaning. Option (c) is the opposite. Option (d) is a nonsensical interpretation.

**Rule: Understanding Similes.** The simile 'as sober as a judge' means to be very serious, sensible, and not under the influence of alcohol. A judge is stereotypically a serious figure. This seriousness inspires trust in their opinion. Option (a) is the correct definition. Option (b) is a literal interpretation of 'judge'. Options (c) and (d) are the opposite of the qualities implied.

**Rule: Understanding Idiomatic Expressions.** The idiom 'back to square one' means to have to start a process again from the very beginning because a previous attempt was unsuccessful. A failed prototype is a clear reason to start the design process over. Option (a) is the correct definition. Option (b) is a literal misinterpretation. Option (c) is an understatement. Option (d) means to quit, not to restart.

**Rule: Understanding Idiomatic Expressions.** The idiom 'put a spin on something' means to present information in a particular way, often to create a favorable or specific impression. A 'new spin' means a new angle or interpretation. Option (b) is the correct definition. Option (a) is a literal misinterpretation. Option (c) is a possible but not necessary outcome. Option (d) is the opposite.

**Rule: Understanding Idiomatic Expressions.** The idiom 'a rule of thumb' refers to a practical and approximate method for doing something, derived from experience rather than precise science. Double-checking one's work is a general principle for ensuring quality. Option (b) is the correct definition. Option (a) is a literal misinterpretation. Option (c) is incorrect as a rule of thumb is often flexible. Option (d) is the literal origin but not the modern figurative meaning.

**Rule: Understanding Idiomatic Expressions.** The idiom 'ring true' means to seem authentic and truthful. The sentence uses the negative ('does not ring true') to mean that the claim seems false, especially when contrasted with 'reality'. Option (a) is the correct definition. Option (b) is a literal misinterpretation. Option (c) is the opposite. Option (d) is about popularity, not truthfulness.

**Rule: Understanding Idiomatic Expressions.** The idiom 'on pins and needles' describes a state of being very anxious or nervous about something that is going to happen. Waiting for important results is a classic cause of this feeling. Option (c) is the correct definition. Option (a) and (d) are literal misinterpretations. Option (b) is the opposite.

**Rule: Understanding Idiomatic Expressions.** The idiom 'a fly on the wall' refers to a person who is able to observe a situation without being noticed. This allows them to see and hear things they otherwise would not. Option (b) is the correct definition. Option (a) is the literal meaning. Option (c) is the opposite of being unperceived. Option (d) is a different status.

**Rule: Understanding Idiomatic Expressions.** The idiom 'get down to brass tacks' means to begin considering the fundamental, practical details of a matter. Discussing the 'actual cost' is moving from generalities to specifics. Option (a) is the correct definition. Option (b) is a literal misinterpretation. Options (c) and (d) are the opposite of the idiom's meaning.