Four Criminals Engage in a Drug Dealing Enterprise, Where All

Four criminals engage in a drug dealing enterprise, where all four are actively dealing drugs together. When they are arrested the police find a fully automatic Tech-9 weapon. The other three criminals stated they had no idea the fourth criminal had a weapon. All four were charged in Federal Court.

A) Under common law rules, what was required in order to prove the crime of conspiracy?
B) Proof of the criminal conspiracy
C) An overt act
D) Any act in furtherance of the conspiracy
E) Any act, regardless if it furthered the conspiracy