which is an example of using a natural resource efficiently?

A turning off the water when you are brushing your teeth
b wearing sunscreen when you go out in the sun
c drinking from a water bottle and the throwing it in the trash
d watering the lawn on days it has rained

A turning off the water when you are brushing your teeth.

The example of using a natural resource efficiently is option D: watering the lawn on days it has rained.