How does Robespierre suggest “enemies” should be treated?

The American attitude toward the French Revolution has been generally favorable—naturally enough for a nation itself born in revolution. But as revolutions go, the French one in 1789 was among the worst. True, in the name of liberty, equality, and fraternity, it overthrew a corrupt regime. Yet what these fine ideals led to was, first, the Terror and mass murder in France, and then Napoleon and his wars, which took hundreds of thousands of lives in Europe and Russia. After this pointless slaughter came the restoration of the same corrupt regime that the Revolution overthrew. Aside from immense suffering, the upheaval achieved nothing.
Leading the betrayal of the Revolution’s initial ideals and its transformation into a murderous ideological tyranny was Maximilien Robespierre, a monster who set up a system expressly aimed at killing thousands of innocents. He knew exactly what he was doing, meant to do it, and believed he was right to do it. He is the prototype of a particularly odious kind of evildoer: the ideologue who believes that reason and morality are on the side of his butcheries. Lenin, Stalin, Hitler, Mao, and Pol Pot are of the same mold. They are the characteristic scourges of humanity in modern times, but Robespierre has a good claim to being the first. Understanding his motives and rationale deepens our understanding of the worst horrors of the recent past and those that may lurk in the future.

Ithink the answer should be a.