Final answer:
Veiling glare can be caused by a room's color and tonal value, which can create a washed-out view leading to reduced contrast and visual discomfort.
Step-by-step explanation:
One of the causes of veiling glare is a) The room's color and tonal value. Veiling glare is a type of visual discomfort that can occur when a bright or reflective surface in the vicinity causes a washed-out appearance to the rest of the view, leading to reduced contrast and difficulty in seeing detailed information. It is important for an effective work environment to manage the lighting and reflective surfaces appropriately, as these factors can impact visual performance and cause discomfort.