Answer:
b. Petrograd
Step-by-step explanation:
Both the February Revolution and the October Revolution occurred in 1917 in Saint Petesburg, which was known at the time as Petrograd, in honor of its founder, Peter the Great.
The February Revolution resulted in the end of the Russian Empire, and the abdication of the tsar Nicholas II, while the October Revolution resulted in the ascent to power of the Bolshevik Party, led by Lenin, and the foundation of the Soviet Union.