Question

review the fourth and fifth paragraphs.
the spreading rates of ridges vary. some spread quite slowly, no more than one to three centimeters per year, while others spread at rates approaching ten to twenty centimeters per year. the rate of spreading influences the topography, or physical features, of the ridge. a slowly spreading ridge has a steep, irregular topography and is relatively narrow, while a faster spreading rate produces a much wider profile and more gentle slopes.
two of the most carefully studied mid - ocean ridges are the mid - atlantic ridge and the east pacific rise. the mid - atlantic ridge runs down the center of the atlantic ocean, slowly spreading at a rate of two to five centimeters per year and forming a dramatic rift valley that is about the depth and width of the grand canyon. in contrast, the east pacific rise spreads quickly, at a
how do the fourth and fifth paragraphs work together?
they describe a general phenomenon and then consider two examples.
they present a hypothesis and then prove it with two conclusive examples.
they describe a theory and then acknowledge there are only two good examples.

Explanation:

The fourth paragraph describes the general phenomenon of varying spreading - rates of ridges and their impact on topography. The fifth paragraph then gives two specific examples (Mid - Atlantic Ridge and East Pacific Rise) of mid - ocean ridges to illustrate the points made in the fourth paragraph.

Answer:

They describe a general phenomenon and then consider two examples.