Analogy — “Nuts : Bolts”. Choose the pair that mirrors a fixed, conventional word duo that forms a well-known collocation or complementary set.

Introduction / Context:
“Nuts and bolts” is a set phrase referring to the essential practical details of something and also names two complementary hardware items commonly paired. The analogy requires recognizing a similarly entrenched, conventional pairing rather than an antonym pair or an adjective–noun phrase that is not a fixed collocation.

Given Data / Assumptions:

• Nuts and bolts are complementary and form a stock phrase.
• The correct choice should be a well-known fixed duo rather than an arbitrary or opposite pairing.
• Only one option should match the collocation/complement pattern closely.

Concept / Approach:
Test each option for set-phrase status and complementarity. A strong collocation is recognizable, idiomatic, and used as a unit (similar to “nuts and bolts”).

Step-by-Step Solution:

Verification / Alternative check:
Both “Nitty : Gritty” and “Salt : Pepper” are strong pairs. However, “nuts and bolts” and “nitty-gritty” share the idiomatic meaning “practical essentials,” making this the best semantic parallel.

Why Other Options Are Wrong:
They are either not idiomatic duos, are antonyms, or are adjective–noun descriptions rather than fixed collocations with shared semantic force.

Common Pitfalls:
Selecting any two commonly co-occurring words without checking for idiomatic unity and meaning equivalence.

Final Answer:
Nitty : Gritty