Which transformation allows a form to retain its identity after a change in volume?

The transformation that allows a form to retain its identity after a change in volume is dimensional transformation. This concept revolves around the idea that a form can undergo a change in size, shape, or volume while maintaining its essential characteristics and recognition as the same entity. Dimensional transformation emphasizes the preservation of the fundamental aspects or "identity" of the original form, despite alterations in its physical size or geometric configuration.

In contrast, other options focus on different aspects of transformation. Subtractive transformation typically involves the removal of material from a form, which may significantly alter its identity. Additive transformation involves adding elements to a form, which can also change its original characteristics and perception. Form alteration generally refers to any modification of a shape without the specific emphasis on identity preservation that dimensional transformation entails. Thus, dimensional transformation is the most suitable answer for the definition provided.