The answer is D) fruits and vegetables that do not spoil easily
You can eliminate B and C, since those two are clearly not positive outcomes (I doubt anybody would want more viruses and fewer animals on Earth!)
A is a little less obvious; however, genetically manipulating crops to have a slower growth rate would be a negative effect on the harvest (and it's probably something most farmers wouldn't want to do anyway.)
So, the answer is D. This makes sense, since having fruits and veggies that don't spoil easily would be a benefit so they can have longer shelf lives.
Hope this helps :)