Maximilien Robespierre and the Jacobins are
best known for
(1) instituting the Reign of Terror
(2) protecting freedom of religion
(3) supporting the reign of King Louis XVI
(4) sending French troops to fight in the
American Revolution



Answer :

Maximilien Robespierre and the Jacobins are best known for "(1) instituting the Reign of Terror" although it should be noted that many people played this role as well. 
The correct answer is (1) instituting the Reign of Terror

After the French revolution, they instituted the reign of terror which was all about killing anyone who was perceived to be a political opponnent. They had fake trials, or sometime no trials at all, and would just be executed. The funniest thing is that eventually Robespierre was also executed according to these same laws.