One Technique for the Detection of Neutrinos from Outer Space

One technique for the detection of neutrinos from outer space involves the reaction of neutrinos with protons in a water tank,with the resulting high-speed positrons,or positive electrons,then generating Cerenkov radiation in the water.How is the Cerenkov radiation produced?

A) by the passage of the charged positron through the water at a speed greater than the speed of light in a vacuum
B) by the recombination of the positron with a proton to produce neutral hydrogen and Balmer series line emissions
C) by the annihilation of a negative electron in the water by the positron
D) by the charged positron moving in the water faster than the speed of light in water