The correct answer is C) unite under the new constitution.
In this quotation, the Consuls of the Republic asked the people of France to unite under the new constitution.
During the coupe of Brumaire, the Directory in France was defeated in November 1799. That is when the Consulate became the form of government in France, during those difficult times of armed conflicts and the death of many French people. Napoleon Bonaparte was a consul before becoming an Emperor of France, and then the members of the government asked the French people to unite under the new constitution.