Answer:
B. greenhouse gases produced by burning fossil fuels
Step-by-step explanation:
Climatologists, or climate scientists, believe that Earth’s climate is changing in dramatic and possibly dangerous ways. Temperatures worldwide are rising. Climatologists think that this is due to greenhouse gases, produced by the burning of fossil fuels such as coal or gasoline. These gases trap heat in Earth’s atmosphere. As a result, they believe, ice sheets are melting and sea levels are rising, threatening coastal communities in the United States and Canada. Climate change is also causing droughts, severe storms, and flooding that threaten people and other living things in both countries.