reflecting light to form images measuring the mass of molecules growing bacteria in a controlled setting observing the strength of physical forces
I gave my students this multiple choice question: What are petri dishes used for in a lab?

Only one answer is correct among these 4 choices:
- reflecting light to form images
- measuring the mass of molecules
- growing bacteria in a controlled setting
- observing the strength of physical forces

Could you tell me which one is correct?

growing bacteria in a controlled setting