Sentence improvement — Correlative comparison: choose the correct ‘‘the more..., the more...’’ structure to improve ‘‘The more they earn, more they spend.’’ for precise comparative balance in English grammar.

Given sentence
The more they earn, more they spend.

Concept/Approach
Correlative comparatives require the definite article in both clauses: ‘‘The more..., the more...’’ This balances the structure and is the standard idiom.

Option analysis
A: More they earn, more they spend — Missing ‘‘the’’ in both parts.B: More they earn, the more they spend — Half-correct; the first half still lacks ‘‘the’’.C: The more they earn, the more they spend — Fully correct correlative form; concise and idiomatic.D: No improvement — Original is unbalanced.

Common pitfalls
Dropping the article in one clause makes the construction sound incomplete or colloquial rather than standard.

Final Answer
The more they earn, the more they spend