D. Encouraging recycling programs
A. wouldn't be the answer because landfills just put more trash into the earth. It takes alot of years for those items to break down and decompose.
B. Finding a new source of coal isn't going to last the rest of our time on Earth, it too will eventually run out.
C. Increasing consumption is going to be that we have even more extra that we don't know what to do with.
D. Encouraging recycling programs is your best answer because it gives the best opportunity for things to be reused or broken down to be made into something else.