The permeability of a material refers to: a) the ease with which a stream erodes material b) the volume of air space in a material c) the ability of water to flow through a material d) a meandering stream's movement across the underlying bedrock.

Answer: The ability of water to flow through a material.

Explanation:

The permeability of a material is the ability of liquids (in this case water) to flow through a material such as: rocks, plants, soil etc.

The level of permeability of a material depends on the ease with which liquids pass through it.