Final answer:
A scientific theory is a well-documented and evidence-based explanation for phenomena in nature, going beyond mere speculation or hypotheses, and capable of making accurate predictions.
Step-by-step explanation:
In science, a theory is not merely a speculative guess or personal conviction. It represents a robust and comprehensive explanation of an important aspect of nature that has been repeatedly tested and supported by a significant amount of evidence. The proper definition, among the provided options, would be an explanation that is well documented and consistent with the evidence. Contrary to everyday language where a theory might imply a hunch, in the scientific community, a theory encompasses the cumulative understanding and findings from various experiments and observations over time.
Scientific theories allow researchers to make predictions about phenomena that have not yet been observed. They are subject to rigorous scrutiny through the scientific method, adapting and solidifying with new discoveries that align with or challenge their predictions. A theory is different from a hypothesis, which is an initial, testable conjecture. Once a hypothesis is extensively tested and validated, it may contribute to the creation of a scientific theory if it consistently explains a broad scope of phenomena.