If the prosecution does not make a selection, can the court compel the jury to unanimously agree upon the act or acts constituting the crime?

If the prosecution does not make a selection, the court has a sua sponte duty to give an instruction stating that the jury must unanimously agree upon the act or acts constituting the crime. (People v. Russo, supra, 25 Cal.4th at p. 1132, 108 Cal.Rptr.2d 436, 25 P.3d 641.) CALCRIM No. 3500, the instruction on unanimity, provides in pertinent part: The People have presented evidence of more than one act to prove that the defendant committed this offense. You must not find the defendant guilty unless you all agree that the People have proved that the defendant committed at least one of these acts and you all agree on which act (he/she) committed.