laws passed by the government Internet sites discussing star formation pictures of stars of different ages evaluation of data by many scientists
I gave my students this multiple choice question: Which of these is required to support the theory of star formation?

Only one answer is correct among these 4 choices:
- laws passed by the government
- Internet sites discussing star formation
- pictures of stars of different ages
- evaluation of data by many scientists

Could you tell me which one is correct?

evaluation of data by many scientists