El niño events are characterized by: warm water piling up near indonesia. a very strong cold current flowing along the eastern edge of south america. strengthening of the ne trade winds. pooling of unusually warm water in the eastern tropical pacific.

The correct answer is D. Pooling of unusually warm water in the eastern tropical Pacific.

Explanation

The Niño phenomenon is a climatic event that is related to the warming of the equatorial eastern Pacific Ocean. This phenomenon usually has great effects in the continental zone of equatorial America, because it produces abundant rains and in some areas it causes the fish to move. The irruption of these warm waters is due to the atmospheric difference between the eastern or western Pacific Ocean. So, the correct answer is D. Pooling of unusually warm water in the eastern tropical Pacific.

I got Oligarchy. you can look it up just to double check though.