The bloodiest period in the French Revolution was the Reign of Terror. Option A is correct.
Maximilien Robespierre Led the Reign of Terror, which claimed the lives of 27,000 men, women, and children and protracted one year out of the 10 years of the French Revolution. 17,000 people were executed and 10,000 others died in prison. Admittedly, this period was an exceptionally chilling moment in the revolution.
