Explanation:

Only statements 1&3 are correct.

• PDO is a long-term climate pattern that affects the temperature of the Pacific Ocean and the weather patterns around it. During a positive phase of PDO, warmer sea surface temperatures are observed in the central and eastern Pacific, while cooler temperatures prevail in the western Pacific. ENSO with a positive PDO is generally not good for India but when linked with a negative PDO, it brings more rain to India.

• The PDO has a longer timescale than phenomena like El Niño and La Niña, spanning decades rather than just a few years.

Hence option 2nd is correct.