Answer:
The Earth's crust that is located furthest away from the center of a mid-ocean ridge is:
Older: The farther away from the center of the mid-ocean ridge, the older the crust becomes. This is because new crust is continually formed at the ridge center and moves away in opposite directions.
Thicker: As the crust moves away from the ridge center, it cools and contracts, becoming thicker.
Less dense: The older, thicker crust is also less dense than the newly formed crust at the ridge center.
Therefore, the correct options are: older, thicker, and less dense.