What is the test for establishing guilt beyond a reasonable doubt in a sexual assault case?

^2. "In determining whether the evidence is sufficient to support a conviction . . . , 'the relevant question is whether, after viewing the evidence in the light most favorable to the prosecution, any rational trier of fact could have found the essential elements of the crime beyond a reasonable doubt.' [Citations.] Under this standard, 'an appellate court in a criminal case . . . does not ask itself whether it believes that the evidence at the trial established guilt beyond a reasonable doubt.' [Citation.] Rather, the reviewing court 'must review the whole record in the light most favorable to the judgment below to determine whether it discloses substantial evidence -- that is, evidence which is reasonable, credible, and of solid value -- such that a reasonable trier of fact could find the defendant guilty beyond a reasonable doubt.' [Citation.]" (People v. Vy (2004) 122 Cal.App.4th 1209, 1224, italics omitted.) "In deciding the sufficiency of the evidence, a reviewing court resolves neither credibility issues nor evidentiary conflicts. [Citation.] Resolution of conflicts and inconsistencies in the testimony is the exclusive province of the trier of fact. [Citation.] Moreover, unless the testimony is physically impossible or inherently improbable, testimony of a single witness is sufficient to support a conviction. [Citation.]" (People v. Young (2005) 34 Cal.4th 1149, 1181.)