When a True Presumption Operates,the Jury Is Told

When a true presumption operates,the jury is told:

A) that they may find a presumed fact to exist even when there is no evidence of the presumed fact,other than the evidence of the basic fact.
B) that they must find a presumed fact to exist even when there is no evidence of the presumed fact,other than the evidence of the basic fact.
C) that they may find a presumed fact to exist.
D) that they must find a presumed fact to exist.