What percentage of carbohydrates do plants use as fuel for cellular respiration?
a) 50%
b) 25%
c) 75%
d) 100%

What percentage increase in the concentration of CO2 in the atmosphere has occurred since the start of the Industrial Revolution?
a) 50%
b) 25%
c) 75%
d) 100%

What percentage of greenhouse gas emissions is accounted for by deforestation?
a) 10%
b) 25%
c) 50%
d) 75%