According to Hess’s theory, what might happen if the magma under a mid-ocean ridge cools? The magnetic stripes might reverse direction. The deep-ocean trench might become deeper. The crust at the ridge might form more quickly. The plates on either side of the ridge might stop moving.

Pj conducts an experimental study on the effects of soft music during high stakes science testing. he randomly assigns students at the school. in one condition he does not provide music for testing while in the other group he does provide the music. he administers a pretest at the beginning of the year and a posttest at the end of the year. pj’s design is best described as a: a.static group comparisonb. pretest-posttest control group designc.control-group-time-series designd. nonrandomized control-group pretest-posttest design