The correct answer is D. A period of scientific and philosophical development.
Step-by-step explanation
The Enlightenment also called "Age of Enlightenment" was a philosophical and scientific movement initiated in Europe during the Eighteenth century that spread throughout the world. It was characterized by the great advance and cultural modernization and the diffusion of the new «Ideas» based on scientific knowledge, replacing the structure of the Old Regime, of the Middle Ages. So, the correct answer is D. A period of scientific and philosophical development.