The El Nino Begins to Weaken and Eventually Terminates When

The El Nino begins to weaken and eventually terminates when

A) the leading edge of the cold Kelvin wave finally reaches the eastern coast of South America.
B) cold water spreads out away from the equator, bringing warm upwelling waters from depth.
C) cold water converges on the equator, bringing cold upwelling waters from depth.
D) warm water spreads out away from the equator, bringing cold upwelling waters from depth.