All of the answers seem to be technically correct. But the question uses the key term "main" so the best match would be "secondary," answer #3. The answers #1, 2, and 4 are roughly similar to each other in their extreme specificity, beyond the specificity of the question. But only answer #3 keeps itself somewhat vague, consistent with the question.
This is a frustrating kind of question! Your teacher is mean. I'd prefer to get questions where the answers are provably correct or incorrect, instead of this style of question where you choose the best from 4 correct answers.