For many years, experiments showed that light had wave-like properties. For this reason, scientists described light as a wave. More recently, experiments produced data that could not be explained by the wave theory of light. The idea of particle properties was introduced. Why did the theory of light change over time?

The theory was too old and needed to be updated.
New scientists did not agree with the older theory.
The scientific question changed, so the theory had to change.
Repeated experimentation introduced new discoveries.