HELP please
Youngest to oldest

The youngest would start from the bottom the oldest would be the very top

Explanation: so let me show you why. at the mid-atlantic ridge there is more and more crust being made in the midle. As it grows the old crust that got push up gets pushed up wards. and is stacked with the rest of the other crust. the image i put with this should help, a little bit more. I this helps.

i think the answer is

mass

1. efficient use of space

2. elimination of groundwater contamination

3. energy generation

4. lower carbon footprint