What is the term for the horizontal surface connecting different levels in a multi-story building?

The term that accurately describes the horizontal surface connecting different levels in a multi-story building is "floor." Floors serve as the structural surfaces that people walk upon, and they also play a critical role in bearing loads, providing stability, and supporting the overall design of the building.

In construction terminology, floors are typically made of various materials depending on the building’s requirements, such as concrete, wood, or composite materials. Each floor can provide a level space for various functions, including living areas, offices, and mechanical rooms, which is fundamental in both residential and commercial structures.

The other terms listed, while related to construction, do not specifically refer to the horizontal surfaces of a building. A "plank" refers to a flat piece of timber, which can be part of a floor but is not synonymous with the term. "Deck" can refer to an exterior flat surface or platform, often related to outdoor spaces rather than interior levels of a building. "Area" is a more generalized term referring to a measured space and does not capture the structural aspect specific to floors.