Only Two of the Major European Powers, Great Britain and Russia

Only two of the major European powers, Great Britain and Russia, avoided major upheaval in politics in 1848 and 1849.What did Tsar Nikolai do to suppress revolt?

A) He followed such conciliatory policies that his opposition gained no traction.
B) He was such a friendly ruler that the general public always favored him.
C) He had created an effective system of police repression.
D) He ensured that there were no aggressive or violent Russian anti-establishment radicals.
E) He kept Russia isolated from European developments.