Final answer:
An unconsolidated, medium-grained sand with clay coated sand grains would be an effective filter for removing unwanted pollutants from water.
Step-by-step explanation:
An unconsolidated, medium-grained sand with clay coated sand grains would be an effective filter for removing unwanted pollutants from water. When water containing pollutants passes through the filter, the clay coated sand grains act as an adsorbent, attracting and trapping the pollutants on their surfaces. This type of sand filter is commonly used in wastewater treatment plants and can effectively remove various pollutants such as heavy metals, organic compounds, and suspended solids.