gene flow genetic drift natural selection random mutation
I gave my students this multiple choice question: A population of plants growing on an island consisted of two varieties, one with thorns and the other without. Over a period of many years, the variety with thorns gradually disappeared. Which process most likely brought about this change in the plant population?

Only one answer is correct among these 4 choices:
- gene flow
- genetic drift
- natural selection
- random mutation

Could you tell me which one is correct?

natural selection