Definition: This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.
Input: Historically, pubs have been socially and culturally distinct from cafés, bars and German beer halls. Most pubs offer a range of beers, wines, spirits, and soft drinks and snacks. Traditionally the windows of town pubs were of smoked or frosted glass to obscure the clientele from the street but from the 1990s onwards, there has been a move towards clear glass, in keeping with brighter interiors.
Output:
Why were the windows of town pubs made of smoked or frosted glass traditionally?