Which of the following is NOT a type of tree trimming?

The term "over trimming" is not recognized as a standard type of tree trimming. In the context of tree care, trimming usually refers to specific practices aimed at maintaining tree health and aesthetics, such as removing dead or diseased branches, improving structure, or controlling growth. Conversely, "under trimming," "through trimming," and "natural trimming" denote particular methodologies or styles of trimming that are commonly discussed within arboriculture.

"Under trimming" typically refers to the practice of trimming the lower branches of a tree, while "through trimming" may indicate a technique used to thin out branches to allow light and air penetration. "Natural trimming" often relates to pruning methods that mimic natural growth patterns to maintain the tree's overall health and appearance. Therefore, since "over trimming" does not align with established practices and may suggest a harmful approach that could damage the tree, it is identified as the correct choice for this question.