It seems unlikely that all four are wrong, but one or two might be. But it's hard to change the theory of the sun without spoiling the agreement with solar oscillation observations. It is known that there are three types of neutrinos. The experiments only detect one kind. Maybe the detectable neutrinos are transformed into undetectable neutrinos as they pass out of the sun.
Particle physicists consider the last solution to be fairly plausible.
If it turns out to be true, an astronomical puzzle will again have led us to new fundamental physics. The principles of stellar structure that we have discussed can be used to construct a detailed model of the sun, which can be tested against observations. Given the mass, composition, and age of the sun, the model correctly predicts the radius and luminosity of the sun. Solar oscillations can be measured precisely using Doppler shifts. Four experiments detect solar neutrinos, providing direct evidence that nuclear fusion occurs in the sun.