Katherine has a physics exam tomorrow. however, a free lecture by one of her favorite authors is taking place this evening. katherine can either attend the lecture or study for her exam. katherine's opportunity cost of attending the lecture is:

The reign of terror describes which period during the french revolution? a. when napoleon led a coup d'etat and seized power b. when the republic executed thousands of citizens c. when france was still a monarchy under king louis xvi d. when other european kingdoms attacked france