Earthquakes produce
_that travel though earth

analysis of the earth's internal structure is made possible because earthquakes produce vibrations called seismic waves. these waves travel through the interior of the earth and can be measured with sensitive detectors called seismographs.

fertile good for trade etc

d. i assume the underlined word is "role." reformat if it isn't.

explanation:

role is closest to part because when replacing words, "playing a vital decision," "playing a vital activity," and "playing a vital dollar" don't make logical sense. the only meaningful choice is "playing a vital part."

this fits one of merriam-webster's definitions of role: "a function or part performed especially in a particular operation or process."