Answer:
D. Commensalism
Explanation:
The relationship between a remora and a shark is an example of commensalism - it's good for one side but neither good nor bad for the other. The remora attaches itself to the shark and gets the benefit of eating the shark's leftovers, but there is no harm or benefit for the shark, and the shark doesn't eat the remora like in a predator/prey relationship.
What does the problem says
To increase the amount of food produced by corn crops, the farmer could select for more cobs on the corn.
