() the northern portion of canada is covered by boreal forests, which are characterized by
a. replanted rows of oak trees.
b. thickly grown rain forests.
c. dense coverings of pine trees.
d. sparsely placed deciduous trees.

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.

a social contract.

"a social contract is an agreement between citizens and their leader where the citizens give up certain freedoms in exchange for protection. the constitution of the united states is an example of a social contract."