Which feature distinguishes an even-span greenhouse from a lean-to?

• A. It has a curved roof
• B. It shares a gutter with another structure
• C. It is freestanding and not attached to a building
• D. It uses a sawtooth roof

Answer: (C)

The main idea is whether the greenhouse stands on its own or is built against another structure. An even-span greenhouse is freestanding, with its own framing and foundation, so it can stand independently and is not attached to any building. A lean-to, on the other hand, is attached to a building along one side, sharing that wall and often using the building’s foundation and roof for support and drainage. That attachment to a larger structure is what truly distinguishes a lean-to from an even-span.

So, the best answer is that the structure is freestanding and not attached to a building. Curved or sawtooth roofs aren’t defining features by themselves, and sharing a gutter is a consequence of being attached rather than a universal trait.