measured with a metric ruler measured with a spring scale observed with the senses observed with a hand lens
I gave my students this multiple choice question: The hardness, odor, and taste of an object can all be

Only one answer is correct among these 4 choices:
- measured with a metric ruler
- measured with a spring scale
- observed with the senses
- observed with a hand lens

Could you tell me which one is correct?

observed with the senses