Marx Called Religion "The Opiate of the Masses" Because

Marx called religion "the opiate of the masses" because

A) opium was served during Mass in the Russian Orthodox Church.
B) people feel better after attending religious services and, therefore, have the strength to combat injustice.
C) he was both highly religious and an opium addict.
D) he said it persuades people to accept an unjust system rather than work to change it.