Answer:
1 is a risk 3 is a benifit!
Explanation:
Hope this is right and helps
I think the answer is to throw away all uneaten and excess food...etc
We could possibly use water as a fuel source, rather than fossil fuels (which are limited)
Science has already developed something of the sort, and with using water as a fuel source for say vehicles and such, it's inevitable for a positive change to happen because there would be less carbon monoxide; which means less polution.
