What is the test for unanimity in a jury verdict in a sexual assault case?

A trial court must instruct jurors that they must unanimously agree that defendant committed the same specific criminal act "'when conviction on a single count could be based on two or more discrete criminal events,' but not 'where multiple theories or acts may form the basis of a guilty verdict on one discrete criminal event.' [Citation.] In deciding whether to give the instruction, the trial court must ask whether (1) there is a risk the jury may divide on two discrete crimes and not agree on any particular crime, or (2) the evidence merely presents the possibility the jury may divide, or be uncertain, as to the exact way the defendant is guilty of a single discrete crime. In the first situation, but not the second, it should give the unanimity instruction." (People v. Russo (2001) 25 Cal.4th 1124, 1135.)