How Was the "Solar Neutrino Problem," That Is, the Detection

Multiple Choice

How was the "solar neutrino problem," that is, the detection of only a third of the predicted number of solar neutrinos, finally resolved?

A) It was found that the detection system was faulty and missed many neutrinos it should have counted.
B) The energy of the neutrinos to be detected had been miscalculated, and different detectors were required to detect neutrinos in the correct range.
C) The basic physics of the emission of neutrinos in nuclear reactions had been misunderstood, and the predicted number was incorrect.
D) On the way from the Sun to Earth the neutrino beam changes to a mixture of three types of neutrinos, only one of which was being detected.