The statement that is NOT a possible effect of a severe solar storm is:
ERCOT-protected power grids in Texas will keep the power on.
While the Electric Reliability Council of Texas (ERCOT) does manage the power grid in Texas, it is not guaranteed that they would remain unaffected by a severe solar storm. Solar storms can induce geomagnetic storms that can disrupt power grid operations, including those in Texas. The other options listed could indeed be potential effects of a severe solar storm.