What type of buildings are commonly referred to as 'toothpick towers'?

'Toothpick towers' typically refer to a specific type of construction that often features a lightweight wood frame with multiple stories, leading to a slender and tall appearance reminiscent of a toothpick's shape. This term is most commonly associated with podium base structures, where a larger, heavier podium is built at the lower levels, supporting lighter, taller wood-frame construction above.

The design capitalizes on the stability provided by the solid base while allowing for the flexibility and economy of taller wood-frame structures above. This construction style has become more common in urban settings where space is at a premium, fitting the definition of toothpick towers, as they often appear tall and slender due to the framing materials used.

The other choices describe categories or types of buildings but do not encapsulate the specific design and appearance described by 'toothpick towers' in relation to their structural characteristics, such as the combination of a heavy podium with lighter upper frames.