F(x, y) = e−x + y2, e−y + x2 , c consists of the arc of the curve y = cos(x) from − 2 , 0 to 2 , 0 and the line segment from 2 , 0 to − 2 , 0.

The correct answer is b, social stratification is needed for a society to exist. marxist theory regarding social stratification is that due to the differing economic capacities among people in society, a natural separation occurs between those that own the means of production and those that sell their labour in the production chain. 

Not the answer but here is the graph.