Cupping will generally be the first indication of abnormal moisture levels in hardwood flooring as the ______ and sides of the board absorb moisture.

Cupping in hardwood flooring occurs when the edges of the boards become higher than the center, which is primarily due to moisture absorption. In this process, moisture typically enters the wood from the bottom and sides of the boards, while the top remains less affected initially.

While all of the choices relate to different parts of the board, the correct focus is on the bottom and sides. This is where moisture is likely to enter the wood first, leading to the alteration in shape that manifests as cupping. As a result, identifying moisture issues early is crucial for effective water damage restoration and prevention of further warping or damage to the flooring.