Correct Option: D

befog (Verb) : to make somebody confused
enlighten (Verb) : to give somebody information so that he may understand something better
slander (Verb) : to make a false spoken statement about somebody that is intended to damage the good opinion that people have of him
bemoan (Verb) : to complain or say that you are not happy about something
darken (Verb) : to become dark ; to make something dark ; to become/make somebody unhappy or angry