using coal to generate electricity discovering a new species of snake developing an antibiotic to treat infections changing the definition of the term planet
I gave my students this multiple choice question: In science, old ideas can be changed when new discoveries alter existing information. Which situation is most likely an example of a rethinking of an existing idea?

Only one answer is correct among these 4 choices:
- using coal to generate electricity
- discovering a new species of snake
- developing an antibiotic to treat infections
- changing the definition of the term planet

Could you tell me which one is correct?

changing the definition of the term planet