A small piece of potato

Answer: Option B

One word substitute is Chip.

Chunk: a thick, solid piece of something.
Chip: a thin slice of food (typically potato) made crisp by being fried, baked, or dried and eaten as a snack.
Scrap: a small piece or amount of something, especially one that is left over after the greater part has been used.
Bit: a short time or distance.