单选题 The passage suggests that scientists consider their understanding of gamma-bursts to be

• (A) incomplete because they still have yet to establish a taxonomy of the various types of GHBs they have observed
• (B) adequate enough to redirect research toward other more perplexing aspects of black holes
• (C) unsurprising, given that scientists have long felt kinetic energy to play a role in the emergence of GHBs
• (D) disappointing because the mechanism by which GHBs become visible is still poorly understood
• (E) in need of confirmation through comparison with another astronomical phenomenon that involves electromagnetic bursts