Why is fine-grit Aluminum oxide preferred for removing corrosion from stressed steel surfaces?

Fine-grit aluminum oxide is preferred for removing corrosion from stressed steel surfaces primarily because it cleans effectively while minimizing the risk of damage to those surfaces. The fine grit provides a balance that allows for the efficient removal of corrosion without stripping away material from the underlying steel or altering its structural integrity, which is crucial in stressed areas where strength is vital. This property helps in maintaining the aircraft's safety and performance characteristics, making aluminum oxide an ideal choice for such applications.

Other options, while they may describe certain aspects of abrasives, do not specifically address the primary concern when dealing with stressed steel surfaces, which is the need to clean without causing further harm.