Final answer:
By-product recovery includes incineration and composting, which recover energy and create soil amendments respectively; thus, the correct answer is d. Both b and c.
Step-by-step explanation:
The methods that involve by-product recovery are incineration and composting. By-product recovery is the process of capturing secondary materials or energy that are produced as a result of waste management or processing. Incineration can recover energy from waste by burning it at high temperatures and converting it into heat or electricity.
Similarly, composting breaks down organic matter to create a nutrient-rich soil amendment, also considered a form of by-product. Open dumping, on the other hand, does not involve by-product recovery. Therefore, the correct answer to the question is d. Both b and c.