Over the past 20 years, the major pollutants in our world have
a. decreased significantly
b. increased significantly
c. stayed at the same levels
d. decreased slightly

b. increased significantly

Explanation:

Over the past 20 years the pollutants concentration in the atmosphere, hydrosphere and lithosphere are increasing considerably. This is due to increase in burning of fossil fuels, deforestation, generation of large volume of biodegradable and non-biodegradable wastes. Thus these factors contributing to the overall increase in the pollution level worldwide.  

humans are now responsible for causing changes in the environment that hurt animals and plant species. we take up more space on earth for our homes and cities. we pollute habitats. human activity often changes or destroys the habitats that plants and animals need to survive.