Why Was Karl Marx Critical of Religion

Why was Karl Marx critical of religion?

A) Marx believed that religion defers happiness and rewards to the afterlife and teaches the resigned acceptance of existing conditions in the earthly life.
B) Marx felt that religions explained existence but provided no explanations for societal advancement.
C) Marx believed that the world's economies were mere reflections of their respective religions.
D) Marx thought that religion influenced humans to think more in terms of philosophy instead of hard science.