The movement known as the Enlightenment focused on the idea that A. people needed to make a return to the natural world. B. faith in God could solve problems. C. some problems could never be solved. D. problems could be solved using human reason.

The correct answer is D. The movement known as the Enlightenment focused on the idea that problems could be solved using human reason. It was the philosophical movement which appeared in Europe and dominated the world of ideas during the 18th century. The ideals of Enlightenment thinkers were liberty, reason, progress, tolerance, and ending of the abuse of the church. Some of the most important personalities of the Enlightenment were Immanuel Kant, Jean-Jacques Rousseau, Rene Descartes, Isaac Newton, James Watt, etc.