Which of these is a natural wood defect rather than a result of improper storage or conditioning?

A knot is a characteristic feature of natural wood that occurs where a branch has grown from the trunk or branch. It is formed as the wood around a branch grows and matures, causing the grain of the wood to change direction and create a solid, often circular area of varying density and color. Knots are an integral part of many types of wood and are considered a natural defect because they happen during the growth process in trees and not as a result of improper handling or treatment of the wood post-harvest.

In contrast, warp refers to a distortion in the wood's shape, which typically occurs as a result of uneven drying or exposure to moisture, making it a consequence of improper storage or conditioning. Splinters arise when wood fibers separate or break away, often due to handling or the condition of the wood rather than its growth characteristics. Checking involves cracks or splits that can develop on the surface of the wood as it dries out too quickly or unevenly, which is also linked to secondary factors rather than a natural feature of the wood itself. Thus, the presence of a knot stands out as a natural defect in wood.