A ford is defined as a shallow stretch within a river or stream that allows people or vehicles to cross by wading or driving through the water.
This term directly matches the description provided in the question: "a shallow stretch of river that may be crossed on feet".
The options Atoll, Reef, and Lagoon are distinct geographical features unrelated to shallow river crossings.
Consider the following pairs: Reservoirs/States
1. Ghataprabha – Telangana
2.Gandhi Sagar – Madhya Pradesh
3. Indira Sagar – Andhra Pradesh
4. Maithon – Chhattisgarh
How many pairs given above are not correctly matched?