Keywords if i'm not mistaken. Length has nothing to do with the type, headings could but not as much as key words, nor does the title.
Answer:
It is a theory because it was developed with many new experiments, and it explained the observations.
Explanation:
A scientific theory is a term in science that serves as a description and explanation to the manifestation of occurrence of events. It involves fully assessed justification for a set of observations or empirical findings.
Hence, in this case, the correct answer is: "It is a theory because it was developed with many new experiments, and it explained the observations."
