The northern portion of Canada is covered by boreal forests, which are generally characterized by "<span>c. dense coverings of pine trees," although this is also a diverse ecosystem when interspersing wetlands as well. </span>
I believe the answer is: c. dense coverings of pine trees.
Boreal forest usually located near the area that is covered by snow, and consisting mostly of pines, spruces and larches. This type of forrest is very common to be found in areas with naturally colder climate such as northern canada and alaska.