**Rule: Understanding Idiomatic Expressions.** The idiom 'a dark horse' refers to a person who wins a race or competition despite being previously unknown or not expected to win. The fact that 'nobody expected him to win' is the key element of this idiom. Option (b) is the correct definition. Option (a) is a literal interpretation. Option (c) describes a favorite, the opposite of a dark horse. Option (d) is unrelated.

**Rule: Understanding Idiomatic Expressions.** The idiom 'like two peas in a pod' is used to describe two people who are very similar in looks, behavior, or interests. Having the 'same interests and opinions' is a clear example of this similarity. Option (c) is the correct definition. Option (a) is the opposite. Option (b) and (d) are literal misinterpretations.

**Rule: Understanding Idiomatic Expressions.** The idiom 'a drop in the ocean' (or 'a drop in the bucket') refers to an amount that is so small as to be insignificant or have very little effect. A small, independent bookstore's sales would be insignificant compared to a giant online retailer's. Option (c) is the correct definition. Option (a) is the opposite. Option (b) is the literal meaning. Option (d) is an unrelated detail.

**Rule: Understanding Idiomatic Expressions.** The idiom 'take something with a grain (or pinch) of salt' means to view something with skepticism and not to interpret it literally or believe it completely. It suggests that the information may be exaggerated or unreliable. Option (b) is the correct definition. Option (a) and (d) are literal misinterpretations. Option (c) is the opposite.

**Rule: Understanding Idiomatic Expressions.** The proverb 'don't wash your dirty linen (or laundry) in public' is advice to not discuss or argue about personal, embarrassing, or private matters in public. It means to keep private issues private. Option (b) is the correct explanation. Option (a) is a literal interpretation. Option (c) is general advice but not the meaning of the idiom. Option (d) is the opposite of the proverb's advice.

**Rule: Understanding Idiomatic Expressions.** The idiom 'on the horns of a dilemma' means to be in a situation where one is faced with a choice between two options, both of which are difficult or unpleasant. Choosing between a career opportunity and family is a classic dilemma. Option (a) is the correct definition. Options (b) and (c) are literal misinterpretations. Option (d) is the opposite.

**Rule: Understanding Idiomatic Expressions.** The idiom 'a different kettle of fish' is used to say that a situation or topic is completely different from another one that has just been mentioned. It emphasizes a distinction. Option (c) is the correct definition. Option (a) is a literal misinterpretation. Option (b) is the opposite. Option (d) refers to a literal kettle.

**Rule: Understanding Idiomatic Expressions.** The idiom 'throw dust in someone's eyes' means to confuse or mislead someone so that they cannot see the truth. Using a 'forged document' is a clear act of deception. Option (c) is the correct definition. Option (a) is a literal interpretation. Option (b) is the opposite. Option (d) is an unrelated action.

**Rule: Understanding Idiomatic Expressions.** The proverb 'when the cat's away, the mice will play' (shortened here) means that people will not follow the rules if the person in charge is absent. It suggests a lack of discipline when supervision is removed. Option (b) is the correct explanation. Option (a) is the literal situation from which the proverb is derived. Option (c) is the opposite of what the proverb implies. Option (d) is nonsensical.

**Rule: Understanding Idiomatic Expressions.** The idiom 'the whole nine yards' means everything, the full extent of something. The detailed and extravagant list of wedding features illustrates that they included everything possible. Option (b) is the correct definition. Option (a) is a literal interpretation. Option (c) is the opposite. Option (d) is an unrelated interpretation.