Lets check out the option's we dont need. Notice that agriculture is the cultivation of animals, plants, fungi, and other life forms for food, fiber, biofuel, medicinal and other products. So it wouldn't be option A because it would of made the animals more calmer and made them eat more which is a big advantage for agriculture when the farmer's needed food. Also it's not option C because a agriculture invention could of caused the seeds to go deeper into the ground which is a good benefit because it would grow more. It's option D because it's not a benefit if there only planting enough for them agriculture is how a person makes money off of food. It's also not option B because more crops being planted would be a benefit for a invention so the answer would have to be option D "Farmers produced only what they needed."
Hope this helps!