Commercial growers scarify, or __________, hard seed coats mechanically or with concentrated sulfuric acid.

Scarification is a process used to break down or soften hard seed coats, which can impede germination. The correct term "scratch" accurately describes the physical action taken to alter the seed coat. This process can be done mechanically or chemically, such as with concentrated sulfuric acid, to help the seed absorb water and oxygen, ultimately facilitating faster germination.

While "cut," "soak," and "peel" could suggest different ways of interacting with seeds, they do not accurately define the method of scarification. Cutting implies a more severe action that could damage the inner seed, soaking refers to immersion in water for hydration rather than specifically addressing the seed coat, and peeling suggests removing layers rather than creating openings. Thus, "scratch" effectively captures the intention and action of scarification, enabling seeds to germinate successfully.