What Major Enlightenment Assumption Did European Thinkers Began to Question

What major Enlightenment assumption did European thinkers began to question during the late nineteenth century?

A) Humans were reasonable creatures capable of investigating natural laws in an objective manner.
B) Time,space,matter,and energy were not independent realities but were relative to each other.
C) The human condition was improved through religious and moral means alone,not through science.
D) Emotions were a more reliable guide to truth than reason.
E) The laws that governed God's universe were utterly beyond human comprehension.