Which ladder material is most susceptible to water damage?

The material that is most susceptible to water damage is wood. Wooden ladders can absorb moisture, which can lead to several issues, such as warping, rotting, and weakening of structural integrity. Over time, repeated exposure to water can compromise the strength of the ladder, making it unsafe for use.

Although other materials like aluminum and fiberglass are resistant to water and do not suffer from rotting or rusting, they may face other issues, such as corrosion or electrical conductivity in the case of aluminum. Steel ladders, while resistant to moisture, can rust if not properly maintained, but they are not as vulnerable to the kinds of damage that can occur with wooden ladders exposed to water. Thus, wooden ladders are especially sensitive to water damage, making them the correct answer.