Correct Option
The question asks to identify the number of pairs that are not correctly matched. Let us evaluate each pair:
- Pair 1: Ghataprabha – Telangana. This pair is incorrectly matched. The Ghataprabha Reservoir is located in Karnataka, on the Ghataprabha River, which is a tributary of the Krishna River.
- Pair 2: Gandhi Sagar – Madhya Pradesh. This pair is correctly matched. The Gandhi Sagar Dam is situated on the Chambal River in Madhya Pradesh.
- Pair 3: Indira Sagar – Andhra Pradesh. This pair is incorrectly matched. The Indira Sagar Dam is constructed on the Narmada River in Madhya Pradesh.
- Pair 4: Maithon – Chhattisgarh. This pair is incorrectly matched. The Maithon Dam is located in Jharkhand, on the Barakar River, a tributary of the Damodar River.
Based on the evaluation, three out of the four given pairs (Pair 1, Pair 3, and Pair 4) are not correctly matched. Therefore, 'Only three pairs' is the correct answer.
Incorrect Options
Options (a) and (b) are incorrect because they state that only one or two pairs are not correctly matched, respectively. As established, three pairs are incorrectly matched.
Option (d) is incorrect because it states that all four pairs are not correctly matched. Pair 2 (Gandhi Sagar – Madhya Pradesh) is correctly matched.