studying bird calls studying exothermic reactions studying the growth of plants studying the diffusion of molecules
I gave my students this multiple choice question: In which of these investigations would pictures from a camera be most useful?

Only one answer is correct among these 4 choices:
- studying bird calls
- studying exothermic reactions
- studying the growth of plants
- studying the diffusion of molecules

Could you tell me which one is correct?

studying the growth of plants