What physical change occurs in wood as it dries out?

When wood dries out, it undergoes a physical change that often results in deformation, such as warping. This is primarily due to the uneven loss of moisture from the wood fibers. As water evaporates, the cellulose and lignin in the wood shrink; if this shrinkage occurs unevenly, it can lead to bending or twisting, causing warping. The structural integrity of the wood can be significantly affected by this deformation, which is why it’s crucial to store and treat wood properly to minimize drying inconsistencies.

Other options do not accurately reflect the typical physical changes associated with the drying process in wood. Increased moisture retention would not occur as wood is losing moisture, while "enhanced strength and durability" can be a characteristic in certain treated woods but isn't directly a result of drying. Additionally, while some woods may change color as they dry, darkening is not a universal phenomenon; various types of wood respond differently in terms of color alteration.