The correct answer is: A. Efflorescence
Efflorescence is a white or grayish powdery deposit that forms on the surface of masonry, concrete, or other building materials. It is caused by the crystallization of salts that have leached out of the material due to exposure to moisture.
Bleaching of paints can be caused by a number of factors, including exposure to sunlight, harsh chemicals, and moisture. When paint is exposed to moisture, it can begin to break down and lose its color. This is especially common in areas that experience high levels of humidity or condensation.
C. Crumbling of plaster can be caused by a number of factors, including exposure to moisture, extreme temperatures, and structural damage. When plaster is exposed to moisture, it can begin to lose its strength and become brittle. This can lead to the plaster crumbling and falling off the wall.
D. Growth of termites is not directly caused by dampness. However, termites are attracted to damp, humid environments. This is because they need moisture to survive and reproduce. If your home has a water leak or other source of moisture, it could attract termites and increase your risk of an infestation.
In conclusion, the correct answer is A. Efflorescence.