Final answer:
Treat the soil, pour in half of it, treat the rest, and then pour in the remaining soil. Hence the correct answer is option C
Step-by-step explanation:
After digging a trench, what you do with the soil depends on the purpose of the trench and the specific circumstances. In general, it is best to treat the soil properly and reuse it if possible, rather than disposing of it. One approach is to treat the soil, pour in half of it, treat the rest, and then pour in the remaining soil, which ensures that the treated soil is evenly distributed throughout the trench.
Hence the correct answer is option C