I can't seem to figure this out, I know that neutrinos have nonzero mass but I don't know how that can help me figure this out

The mass of a neutrino is
zero.
equal to the mass of a proton.
equal to the mass of an electron.
less than the mass of an electron but its actual value is unknown.
equal to the mass of a neutron

To determine the mass of a neutrino, you can use several methods. One approach is to investigate the effects of neutrino oscillations, which occur due to the phenomenon known as neutrino mixing. Neutrino oscillations have been extensively studied through neutrino experiments and observations of neutrino interactions.

Here's how you can use neutrino oscillations to learn about neutrino mass:

1. Neutrino Oscillations: Neutrinos are known to exist in three different types or flavors: electron neutrinos, muon neutrinos, and tau neutrinos. Neutrino oscillations occur when a neutrino of one flavor spontaneously changes into a neutrino of a different flavor as it travels through space. This phenomenon has been experimentally observed and confirmed.

2. Neutrino Mixing and Mass Differences: The occurrence of neutrino oscillations indicates that the three neutrino flavors are not mass eigenstates (neutrinos with definite masses) but a superposition of mass eigenstates. Neutrino mixing is described by a matrix known as the PMNS matrix, which relates the flavor eigenstates to the mass eigenstates.

3. Measurements of Neutrino Oscillations: Experimental studies, such as solar, atmospheric, reactor, and accelerator-based neutrino experiments, have measured the probabilities of neutrino flavor transitions, providing valuable information about the mixing angles and the mass differences between the neutrino mass eigenstates.

4. Neutrino Mass Hierarchy: One crucial unknown in neutrino physics is the neutrino mass hierarchy. It refers to the ordering of the neutrino mass eigenvalues. There are two possible hierarchies: normal hierarchy, where the third mass eigenstate is the heaviest, and inverted hierarchy, where the first mass eigenstate is the heaviest.

5. Neutrinoless Double Beta Decay: Another experimental approach to determine the absolute mass scale of neutrinos is by studying neutrinoless double beta decay. If observed, it would imply that neutrinos are Majorana particles (meaning neutrinos are their antiparticles), and the rate of this process would depend on the effective neutrino mass.

Based on the available experimental data, scientists have determined that the mass of a neutrino is not zero, as previously thought, but its actual value is still unknown. Researchers continue to investigate neutrino properties using various experimental techniques to further constrain the neutrino mass scale and determine its precise value.