1. Jiang- I can appreciate your confusion, because both you and I obviously know more about corn than the writer of this question! I think I'll go with drooping.
2. A is the correct response, though we (AE) use the word riddled most typically in reference to holes made by bullets or shot, not punched.
3. Not sure what "store sugar" might be- maybe processed, granulated sugar as opposed to raw, cane sugar or syrup. I think if the reference was to a large quantity, to be sold off in smaller lots (as you suggest), it would be called bulk sugar.