What we define as normal and abnormal behavior depends on multiple choice evidence of abnormality. empirical research. social context. individual opinion?

I believe the answer is: Social context
Social context would be influenced by the culture, tradition, and moral value in the society around it.
For example,being completely naked might be considered as 'normal' in some parts of eastern europe. But there's no way this exact behavior would be acceptable in eastern Asian culture.

The answer for this question is c