Vast tracts of rainforest have been clear-cut and burned. This practice has increased atmospheric carbon dioxide levels significantly because

a. forest provided a place for the carbon dioxide to be used.
b. burning of the forest released a large amount of carbon dioxide into the atmosphere.
c. grasslands that replaced the forests cannot utilise as much carbon dioxide.

• A

  a and b only

• B

  b and c only

• C

  a and c only

• D

  a, b and c