In this idiom and phrase question, select the option that best expresses the meaning of the expression 'Spick and Span' as used in everyday English.

Introduction / Context:
This question tests your knowledge of common English idioms and phrases. Idioms like 'Spick and Span' are fixed expressions whose meaning cannot be understood simply by translating each word. They often appear in spoken English, newspapers and exams, so you should recognise them instantly and know the idea they convey. Here, the expression describes the condition or appearance of something, usually a room, house or object.

Given Data / Assumptions:
- Idiom: 'Spick and Span'.
- Options: 'High and low', 'Dark and light', 'Neat and clean', 'Happy and sad'.
- Exactly one option captures the accepted idiomatic meaning.
- Standard British and Indian English usage in everyday contexts is assumed.

Concept / Approach:
The idiom 'Spick and Span' is used to praise something that is extremely clean, tidy and well-arranged. It typically describes a home, desk, classroom, uniform or anything else that looks freshly cleaned and perfectly neat. When solving idiom questions, you do not translate word by word but instead recall or learn the fixed meaning. Among the options, you must pick the phrase that matches this idea of perfect cleanliness and orderliness.

Step-by-Step Solution:
Step 1: Recall that if someone says, 'The room is spick and span', they mean the room is very neat, tidy and spotless. Step 2: Examine 'High and low'. This expression usually refers to levels or to searching everywhere, not to cleanliness. Step 3: Examine 'Dark and light'. This option talks about contrasting levels of brightness, not order or cleanliness. Step 4: Examine 'Neat and clean'. This phrase directly describes something that is well-arranged, dust-free and tidy. Step 5: Examine 'Happy and sad'. This option deals with emotional states and has no connection with the condition of a place or object.

Verification / Alternative check:
Substitute each option for the idiom in a sample sentence: 'After the festival, her house was spick and span.' If we say 'her house was neat and clean', the meaning remains identical and natural. Saying 'her house was high and low', 'dark and light' or 'happy and sad' is either meaningless or totally unrelated to cleanliness. Therefore only 'Neat and clean' matches the idiomatic sense used in standard English.

Why Other Options Are Wrong:
'High and low' is wrong because it is used in phrases like 'searched high and low', meaning looked everywhere. 'Dark and light' is wrong because it merely presents a pair of opposite brightness levels, not a condition of tidiness. 'Happy and sad' is wrong because it relates to feelings and emotions. None of these convey the idea of something being spotless and orderly, which is central to 'Spick and Span'.

Common Pitfalls:
A frequent mistake in idiom questions is to guess based on the grammatical pattern of the phrase, such as any pair of opposite words joined by 'and'. However 'Spick and Span' is not about opposites; it is a fixed historical phrase whose modern meaning is unrelated to the literal words. To avoid errors, try to memorise idioms in example sentences and associate them with mental images, such as a freshly cleaned room shining and perfectly arranged.

Final Answer:
The expression 'Spick and Span' means Neat and clean.