C: 4/5
EXPLAINATION
North America is about 9.5 million square miles.
The area of Canada and the US are about 3.8 million square miles each.
3.8 million + 3.8 million = 7.6 million square miles [total area of Canada and US].
7.6 million / 9.5 million = .8 or 80%.
80% = 4/5
