If there is excessive water removal from the Central Valley Aquifer in California, the most direct and likely consequence would be land subsidence. This occurs when the ground above the aquifer sinks as water is extracted faster than it can be recharged. While none of the specific options you've listed directly mention land subsidence, the closest relevant point might be that excessive groundwater extraction can lead to decreased stability in the ground, which could potentially affect fault lines and increase the risk of earthquakes as the geological conditions change.
However, the direct influence on tectonic plates to the extent of causing volcanoes or severe transformations into a desert is not supported by scientific consensus. The long-term effects of excessive water removal may include agricultural impacts and ecosystem changes, but the suggestions in the provided responses are speculative and not the most immediate or scientifically established outcomes.
So, while the first response about faults becoming less stable could have some merit in terms of the geological implications, it's important to focus on land subsidence as a more immediate concern associated with excessive groundwater extraction.