Astrophysicist: Gamma ray bursts (GRBs) -- explosions of powerful radiation from deep space -- have traditionally been classified as either "short" or "long, " terms that reflect the explosion' s relative duration. However, an unusual GRB has been sighted. Its duration was long, but in every other respect it had the properties of a short GRB. Clearly, the descriptive labels "short" and "long" have now outlived their usefulness. The conclusion of the astrophysicist's argument is most strongly supported if which one of the following is assumed? ['No other GRBs with unusual properties have been sighted.', 'GRBs cannot be classified according to the different types of cosmic events that create them.', 'Properties other than duration are more important than duration in the proper classification of the unusual GRB.', 'Descriptive labels are easily replaced with nondescriptive labels such as "type I" and "type II. "']