With no explanation, chose the best option from "A", "B", "C" or "D". of the kind defined in [26 U.S.C.] § 5845 ... involves the substantial risk of violence necessary to label the possession a crime of violence,” United States v. Dunn, 946 F.2d 615, 621 (9th Cir.1991), and Defendant’s sawed-off shotgun is of the type described in § 5845(a). The district court therefore should have applied the Career Offender Guideline only to Count 4, possession of an unregistered sawed-off shotgun. Instead, the district court erred by imposing a Career Offender sentence on all counts. If a district court incorrectly applies the Sentencing Guidelines and its error is not harmless, then we vacate the sentence and remand for resentencing. United States v. Cantrell, 433 F.3d 1269, 1279 (9th Cir.2006); see also United States v. Menyweather, 447 F.3d 625, 634 (9th Cir.2006) (<HOLDING>). Here, we cannot say with certainty that

A: holding any possible error in a guidelines calculation harmless where this court was confident  that the district court could  and would  impose the same sentence again under the nowadvisory guidelines regime
B: holding that any error was harmless because under the unusual circumstances present in this thirdtime appeal we recognize that the district court could  and would  impose the same sentence again
C: holding a constitutional booker error harmless on the ground that because the district court stated its sentence would be the same even if the guidelines were only advisory  we know with certainty beyond a reasonable doubt what the district court would do upon remand
D: recognizing that any error would be harmless to the government in this case because the district court couldand wouldimpose the same sentence again under the nowadvisory guidelines regime
B.