Out of the following options, select the meaning of the idiom "in black and white".

Introduction / Context:
This question tests your understanding of the idiom in black and white. Although the phrase literally refers to the colours black and white, in everyday English it is most often used to describe information or agreements that are clearly written down. Your job is to choose the option that best expresses this idiomatic meaning.

Given Data / Assumptions:

- Idiom: in black and white. - Options refer to different ideas about colour, prejudice, and clarity. - The typical context is legal documents, contracts, or written statements. - The correct meaning must involve something being recorded clearly and officially.

Concept / Approach:
In black and white is used to emphasise that something is not just spoken but actually written or printed in a permanent, visible form. For example, if a rule is in black and white, it means you can see it written in a document. This gives the idea of certainty and proof. The correct option must therefore mention being written or printed clearly, often in an official way, rather than any literal issue with colour vision or prejudice.

Step-by-Step Solution:
Step 1: Recall common sentences like I have it in black and white that my salary will be increased or The agreement is set out in black and white. Step 2: Notice that in both examples, the idiom refers to written proof or documentation. Step 3: Examine option C, which states to have something written or printed clearly in an official and definite form. This matches the typical usage closely. Step 4: Look at option A, to be colour blind, which uses black and white in a literal sense and does not match the idiom. Step 5: Consider option B, to see things as either good or bad with no middle ground. Although related to black and white thinking, that phrase is slightly different and less commonly expressed simply as in black and white. Step 6: Check option D, to be excessively prejudiced, which also does not reflect the core idea of documentation and clarity. Therefore, option C is the best explanation.

Verification / Alternative check:
Test the options in a standard sentence: The terms of the contract are in black and white. Replacing the idiom with option C gives The terms of the contract are written and printed clearly in an official and definite form, which matches the intended meaning. Using the other options would yield strange or illogical sentences, such as The terms of the contract are colour blind, which makes no sense.

Why Other Options Are Wrong:
Option A misinterprets black and white literally and refers to colour blindness, not written proof. Option B refers to a rigid style of thinking, often called seeing things in black and white, but the exact idiom in black and white in this exam context typically points to written documentation. Option D focuses on prejudice and does not connect to the idea of documentation or clarity.

Common Pitfalls:
Students sometimes confuse the idiom in black and white with the phrase black and white thinking, which describes an all or nothing mindset. Context is crucial. Whenever you see the expression used around documents, contracts, terms, or proof, it almost always means written or printed clearly. Learning to check the surrounding nouns for clues helps you choose the right interpretation quickly.

Final Answer:
To have something written or printed clearly in an official and definite form is the correct meaning of the idiom in black and white.