The correct answer is A) the desire for a constitutional monarchy.
One cause of the Decembrist Revolt was the desire for a constitutional monarchy.
Russia was a place with many problems. Indeed, the whole of Russian territory was a political turmoil. Many Russian military officers led thousands of men on December 26, 1825, to protest against the authority of Nicholas 1 after Tsar Alexander 1 had dead.
Under the name of Union Salvation, these military officers and their troops wanted to introduce a constitutional monarchy in Russia. Unfortunately for them, they were defeated and some of them had to leave the country.