The state of california experiences periodic occurrences of severe drought conditions. which weather phenomenon most likely causes this and why? el niño, because of weakening of trade winds el niño, because of strengthening of trade winds la niña, because of increased upwelling of cooler waters la niña, because of decreased upwelling of cooler waters

Option C, La Niña, because of increased upwelling of cooler waters

Explanation:

La Niña is a climatic condition which lowers the temperature of surface ocean water along the west coast of South America. It makes the sea water temperature lower than the normal temperature. Due to lower temperature, higher than normal pressure builds over the central and eastern Pacific, this causes reduction in rainfall. Rainfall reduces as cloud production reduces due to up-welling.  

 Hence, option C is correct