What are the differences between active and passive continental margins? what is the relationship between plate tectonics and the various features? provide an example of each continental margin.

An active margin is a plate boundary in which the plate on which a continent is on is riding over and pushing down the plate. The west coast of North and South America are good examples. On the other hand, a passive margin do not correspond to a plate boundary therefore the drop-off from the land to the sea is gentle.The east costs of North and South America are good examples.

Well, a and b together would be negative. b alone would also be negative.

Why you put last one a? i think is b.