Which practice fits the definition of conservation?

using more of a mineral resource than needed

not using a necessary mineral resource at all

strip-mining a mineral without regard to the surface soil and vegetation above it

recycling cans that contain a material like aluminum

Recycling cans that contain material like aluminum.

Explanation:

-Conservation is defined as the act of preventing an injury, decay, waste or loss of a resource.

-Recycling Aluminium ensures that  its exposure effects to human beings or animals is reduced.

-Also, what is already mined can be recycled for future use as opposed to further mining which has led to extensive land degradation.

wavelength variability is the right one