What is the test for admissibility of evidence of "other acts" in a criminal case?

"Evidence of `other acts' is not subject to Rule 404(b) analysis if it is `inextricably intertwined' with the charged offense." United States v. Beckman, 298 F.3d 788, 793 (9th Cir. 2002). "This exception applies when (1) `particular acts of the defendant are part of ... a single criminal transaction,' or when (2) `"other act" evidence... is necessary [to admit] in order to permit the prosecutor to offer a coherent and comprehensible story regarding the commission of the crime.'" Id. at 794 (citation omitted). Only the second of these scenarios is relevant to our discussion, and we address it first, as it was the primary basis for the district court's finding of admissibility.