The action that can help slow down the process of chemical weathering among the options provided is using less water in industrial areas.
Chemical weathering typically involves reactions between minerals in rocks and water, often accelerated by the presence of acids or other chemicals found in water. By reducing the amount of water used and potentially reducing the runoff and erosion involved, the rate of chemical weathering can be slowed down.
While burning less fossil fuel and other actions may influence environmental conditions and pollution, they do not directly target the chemical weathering process as effectively as managing water use does. Removing clay or iron oxide may also not be practical or effective in the context of slowing chemical weathering in general.