How much must the population of a species decrease over a ten-year period to be classified as endangered? 20%

70%

10%

50%

Why do we perceive objects as retaining their brightness under different lighting levels?

To be or not to be that is da question

Which of these is an example of land degradation? a. containers designed to store pollutants leak. b. fertilizers provide too many nutrients to crops. c. garbage is buried so the land can be reclaimed later. d. a drought kills all the plants in an area, leaving bare land