Read the following excerpt from a US court opinion:
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CWs credibility and his use of a gun. In light of the unrebutted fact of CWs death improperly admitted during the prosecutor’s rebuttal argument, the latter issue was of particular importance, as discussed supra. In sum, given the lost opportunity to confront CW in relation to the unavailable discovery, the admission of the preliminary hearing testimony at trial violated Nofoa’s right to confrontation as guaranteed by article I, section 14 of the Hawaii Constitution and the sixth amendment of the United States Constitution. Thus, we hold that the circuit court erred in allowing admission of CWs preliminary healing testimony at trial We additionally hold that the error was not harmless beyond a reasonable doubt. See State v. Mundon, 121 Hawai'i 339, 368, 219 P.3d 1126, 1155 (2009) . We are unable to say the error was harmless
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What is the most suitable continuation to the opinion? Your options are:
A. holding constitutional error may be harmless if court can  declare a belief that it was harmless beyond a reasonable doubt  quoting state v napeahi 57 haw 365 373 556 p2d 569 574 1976
B. holding that before a federal constitutional error can be held harmless the court must be able to declare a belief that it was harmless beyond a reasonable doubt
C. holding that in order to conclude that federal constitutional error is harmless court must find that error harmless beyond a reasonable doubt
D. holding that a constitutional error is harmless where it can be proved beyond a reasonable doubt that the error complained of did not contribute to the verdict obtained
E. holding that appellate court should review error in trial procedure to determine if it was harmless beyond a reasonable doubt
Reply with [A, B, C, D, E] only.