The soil is removed from the natural site, is treated with acid to leach the heavy metals out, then with a base to neutralize the soil and cause the heavy metals to precipitate out.” What process does this statement describe?

Question

$\begin{array}{1 1} \text{(a)Using scrubbers to clean smokestacks} \\ \text{(b) Using catalytic converters to reduce automobile emissions} \\ \text{(c) Restoring soils contaminated with toxic mine waste} \\ \text{(d) Using lime to restore acidic lakes} \end{array}$