What convergent plate boundary does not include a subduction zone?

Only continental-continental convergent boundaries do not have subduction zones because the two plates have an equal density.

The highest point of a hill (or mountain) is a single point.
a single point can only be precisely marked with a dot. 
putting on a contour line is impossible  on a single point because the contour line is created after multiple points that have the same hight are marked, and after that, all of those points are connected with a line that creates a closed area. so the highest point, as said above, is a single point, there are no other points with the same height, so the only possible way for it to be marked is with a dot, and there is no possibility for a contour line.

C.     is the right answer because it is ask about the soil types has the richest in organic material.

good luck