The Solution to the Solar Neutrino Problem Was

The solution to the solar neutrino problem was

A) the Sun's core is cooling down, producing less neutrinos that expected.
B) 2/3 of the neutrinos transform into a new type during the 8- minute trip to Earth.
C) the Earth's ozone layer absorbs 2/3 of the neutrinos in transit.
D) the corona is opaque to much of the neutrino radiation.
E) our solar energy equations were just wrong, and needed much reworking.