In this idiom question, choose the option that best expresses the meaning of the phrase As daft as a brush.

Introduction / Context:
Idioms are fixed expressions whose meanings cannot be understood by translating each word separately. As daft as a brush is a British English idiom that appears in informal speech and writing. Exams frequently test such idioms to check whether you can recognise their figurative meaning rather than interpreting them literally.

Given Data / Assumptions:
- Idiom: As daft as a brush. - Options: Extremely silly, Artistically inclined, Completely clean, Utterly selfish. - Context is not provided, so you must rely on knowledge of the idiom.

Concept / Approach:
The structure as adjective as is often used for similes, for example as cool as a cucumber or as busy as a bee. In this idiom, daft means silly or foolish. The object, a brush, does not literally have intelligence, so the entire expression humorously exaggerates foolishness. Therefore, the idiom describes someone who is extremely silly or very stupid, not artistic, clean, or selfish.

Step-by-Step Solution:
Step 1: Identify the key adjective daft, which in British English means silly, foolish, or slightly crazy. Step 2: Recognise the pattern as daft as a brush as a fixed idiomatic simile. Step 3: Understand that the idiom emphasises a very high degree of foolishness. Step 4: Compare with options. Extremely silly matches this meaning exactly. Step 5: Artistically inclined does not relate to foolishness at all. Step 6: Completely clean refers to physical cleanliness and ignores the idea of silliness. Step 7: Utterly selfish deals with selfishness, not stupidity, so it is also incorrect.

Verification / Alternative check:
Consider a typical sentence: Everyone else understood the simple instructions, but he behaved as daft as a brush. Here, the context clearly suggests that the person is being very foolish or silly. Replacing the idiom with extremely silly produces a sentence with the same sense and tone. No other option preserves the meaning, which confirms the correctness of that choice.

Why Other Options Are Wrong:
Artistically inclined suggests talent or interest in art and has nothing to do with daftness. Completely clean refers to hygiene or lack of dirt and does not match the mental quality of foolishness. Utterly selfish points to self centred behaviour and not to silliness or stupidity.

Common Pitfalls:
A common problem with idioms is that learners sometimes translate the words literally or guess based on one part of the phrase. Here, brush might mislead someone into thinking about cleaning, so they might wrongly choose completely clean. To avoid such errors, it is important to memorise idioms as complete units along with their figurative meanings and to revise common similes that use as adjective as patterns.

Final Answer:
The idiom As daft as a brush means Extremely silly.