Narmada flowing through a rift valley shows what type of geological structure?

Correct answer: Fault-controlled sunken course

The direct answer is A: a fault-controlled sunken course. A rift valley forms when faults, or large fractures, develop in the crust and the land block between them sinks relative to surrounding land. A river can then use this long, low depression as its channel. The Narmada is a major Indian example and flows westward through a rift valley between structural uplands. Thus its course is controlled mainly by geological structure, not by a delta or mangrove. A is correct because it describes both the fault and the lowered route. B is wrong because a delta is formed at a river mouth by deposition. C is wrong because the rift valley is the relevant feature, not a glacier-controlled source. D is wrong because mangroves and distributaries are coastal delta features. Memory cue: Narmada and Tapi are commonly linked with rift-valley drainage.