Final answer:
Nicholas II's failure to address the rights and demands of his people was a major mistake that contributed to the Russian Revolution.
Step-by-step explanation:
The mistake made by Nicholas II that is NOT mentioned among the options provided is that he did not effectively address the rising discontent and demands for reforms from his people. Although option B mentions his refusal to make significant reforms, this does not cover the extent of his failure in addressing the rights and demands of the people. This mistake ultimately contributed to the Russian Revolution and the downfall of the Romanov dynasty.
Learn more about the mistakes of Nicholas II