Answer: The correct option is D. Put marginal land under cultivation and grow grain on it.
Explanation: From the scenario given above, we can see that a quota will be issued to limit farmers to a flat percentage of previous acreage cultivation, and what this means is that quotas issued will be calculated as a percentage of the farmer's preexisting grain production acreage.
The farmer would therefore benefit from increasing his/her grain production acreage even in cases where some of the new land to be used is suboptimal for grain cultivation.