C the treadmill is the correct answer
Who is this he ?
Without this we can not answer the question
1. reusing
2. incineration
3. source reduction
4. recycling
hope this helps! although I do believe it is one of those opinion questions where no answer is wrong.
explanation: I believe that reusing and incineraton are the two best because they are the least wasteful. And while source reduction and recycling are good they aren't quite as efficient as the other two. Plus they are more time consuming.