Which of these energy sources is most closely related to the harvesting of a corn crop?

I think Biofuel is the energy that is most closely related to the harvesting of a corn crop. Corn is harvested when the tassles turn brown and the cobs stand out from the stem at and angle of 30 degrees. With the sweet corn, when you peel back the husk a little, and press a fingernail into a kernel, it should be soft and secrete a creamy juice.