Of the four given options, choose the most appropriate one.

Correct option is C

The correct sentence is (c) They have built a dam across the river.
Explanation:
· The preposition "across" is appropriate when referring to constructing something that spans from one side of a river to the other.
· The word order in (c) is logical and maintains clarity, following the standard structure: subject + verb + object + adverbial phrase.
Analysis of other options:
· Option (a): Incorrect; "across river" lacks the article "the," making it grammatically incomplete.
· Option (b): Incorrect; "over the river" implies the dam is suspended above the river, which is not the intended meaning.
· Option (d): Incorrect; the word order is awkward and unnatural, making the sentence unclear.
Grammatical Rule: Use prepositions correctly to convey spatial relationships. "Across" is used for something spanning from one side to another, while "over" suggests something above or suspended.
Explanation in Hindi: सही वाक्य "They have built a dam across the river" है।
· "Across" का प्रयोग तब किया जाता है जब कोई वस्तु नदी या स्थान के एक छोर से दूसरे छोर तक फैली हो।
· विकल्प (a) में "across river" बिना "the" के गलत है।
· विकल्प (b) में "over the river" का अर्थ गलत है, क्योंकि यह दर्शाता है कि बांध नदी के ऊपर लटका हुआ है।
· विकल्प (d) में वाक्य का क्रम गलत है।