Along a mid-ocean ridge, rocks moving away from the ridge.
a. become older
b. become younger
c. remain the same age

A. become older

Explanation:

A mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, formed by plate tectonics. This uplifting of the ocean floor occurs when convection currents rise in the mantle beneath the oceanic crust and create magma where two tectonic plates meet at a divergent boundary.They technically would be old rocks because once the lava dries out it will spew out new rock, pushing away the older rock.

d. the weight of the book

it's c. (to reduce the greenhouse effect/carbon gasses)