class discussion. previous knowledge. temperature changes. student observations.
I gave my students this multiple choice question: A student pours a clear liquid from a test tube into a beaker with a clear liquid already in it and notices that the mixture turns pink. The student infers the two clear liquids are different. This inference is a result of

Only one answer is correct among these 4 choices:
- class discussion.
- previous knowledge.
- temperature changes.
- student observations.

Could you tell me which one is correct?

student observations.