In the following aptitude question, each option shows a pair of words where the first word may or may not belong to the general category expressed by the second word. Three word pairs show a correct category relationship between an individual colour and the general term "Colour". One pair breaks this pattern. From the given alternatives, which word pair is the odd one out?

Introduction / Context:
This verbal reasoning question asks you to identify the odd word pair based on logical category relationships. In three of the options, the first word is a specific colour and the second word is the general category "Colour". In one option, this clear category relationship does not hold in the same way. Recognising such classification patterns is common in general aptitude and competitive exams.

Given Data / Assumptions:

• Word pairs given: White – Colour, Blue – Colour, Yellow – Orange, Black – Colour.
• We assume the second word in each pair is intended to be a category or related descriptor.
• We need to find the pair that does not fit the same relationship as the others.
• Basic knowledge of colours and their categories is assumed.

Concept / Approach:
The key concept here is category membership. For three options, the relationship is "X is a kind of Colour". White, Blue and Black are all basic colours, so each of those can be naturally followed by the category word "Colour". In a consistent pair, the second word should act as a broader class containing the first word. We simply check which pair does not show this same one-to-many category relationship.

Step-by-Step Solution:
Step 1: Examine "White – Colour". White is clearly a colour, so the relationship is "White is a Colour". This pair is logically correct. Step 2: Examine "Blue – Colour". Blue is also a basic colour, so "Blue is a Colour" is a valid category relationship. Step 3: Examine "Black – Colour". Black is again a basic colour, therefore the relationship "Black is a Colour" is also logically correct. Step 4: Examine "Yellow – Orange". Both Yellow and Orange are themselves names of individual colours. Here, the second word is not acting as a category that includes the first word. Instead, we simply have two different colours placed together without a clear "is a" category relationship. Step 5: Since three pairs follow the pattern "Specific Colour – Colour (category)" and one pair is "Colour – Colour" without a category link, the odd one out is "Yellow – Orange".

Verification / Alternative check:
You can recast each pair into a sentence: White is a Colour – correct. Blue is a Colour – correct. Black is a Colour – correct. Yellow is an Orange – incorrect, because Orange is not the broader category of Yellow. Only the fourth sentence is logically incorrect, confirming that Yellow – Orange does not fit the same pattern.

Why Other Options Are Wrong:
White – Colour is valid because White is a member of the category Colour. Blue – Colour is valid for exactly the same reason, Blue is also a Colour. Black – Colour is again valid, as Black is a recognised Colour. These three all share a clear "member–category" relationship, unlike Yellow – Orange.

Common Pitfalls:
A common confusion is to overthink the relationship between Yellow and Orange and imagine some hidden connection, such as both being warm colours. However, the test is not about similarity or contrast but about whether the second word is a category label for the first. Another pitfall is to assume that any pair of colours together forms a valid pattern, which is not the intended logic here.

Final Answer:
The pair that breaks the consistent category pattern and is therefore the odd one out is Yellow – Orange.