Option 1 -> La Niña strengthens trade winds, pushing warm water westward causing floods in Australia while Peru/Ecuador experience drought - this is correct about La Niña.
Option 2 -> La Niña conditions typically enhance the Indian monsoon system, bringing better rainfall - this is correct about La Niña.
Option 3 -> La Niña is characterized by cooler than normal sea surface temperatures in the central and eastern tropical Pacific - this is correct about La Niña.
Option 4 -> This describes abnormal warming of sea surface waters - this is actually the definition of El Niño, not La Niña.
Hence, Option 4 -> This statement incorrectly describes La Niña. Abnormal warming of sea surface water in the central and eastern tropical Pacific Ocean is the characteristic of El Niño, not La Niña. La Niña is the opposite phenomenon, featuring abnormal cooling of these waters -> correct