What defines a corrosive substance?

A corrosive substance is specifically defined by its ability to cause damage to living tissue, including skin and mucous membranes, at the point of contact. This characteristic is what primarily distinguishes corrosive materials from other harmful substances. Such substances can cause severe burns or irreversible damage, and this damage can occur quickly upon exposure.

While skin irritation, toxicity when ingested, and the release of harmful fumes are all significant safety concerns associated with various chemicals, they do not meet the stringent criteria used to categorize a substance as corrosive. Corrosive materials directly damage the tissue themselves, which is the fundamental aspect of their classification. This is why option A accurately captures the essence of what defines a corrosive substance in the context of chemical safety and handling.