This task is about writing a correct answer for the reading comprehension task. Based on the information provided in a given passage, you should identify the shortest continuous text span from the passage that serves as an answer to the given question. Avoid answers that are incorrect or provides incomplete justification for the question.

[EX Q]: Passage: Mass production of glass window panes in the early twentieth century caused a similar effect. In glass factories, molten glass was poured onto a large cooling table and allowed to spread. The resulting glass is thicker at the location of the pour, located at the center of the large sheet. These sheets were cut into smaller window panes with nonuniform thickness, typically with the location of the pour centered in one of the panes (known as "bull's-eyes") for decorative effect. Modern glass intended for windows is produced as float glass and is very uniform in thickness. Question: How was the bull's-eye used?
[EX A]: for decorative effect

[EX Q]: Passage: Another potential weapon system for anti-aircraft use is the laser. Although air planners have imagined lasers in combat since the late 1960s, only the most modern laser systems are currently reaching what could be considered "experimental usefulness". In particular the Tactical High Energy Laser can be used in the anti-aircraft and anti-missile role. If current developments continue, some[who?] believe it is reasonable to suggest that lasers will play a major role in air defence starting in the next ten years. Question: When do some people believe that lasers can play a more prominent role in air defence?
[EX A]: in the next ten years

[EX Q]: Passage: Although Bell was, and still is, accused of stealing the telephone from Gray, Bell used Gray's water transmitter design only after Bell's patent had been granted, and only as a proof of concept scientific experiment, to prove to his own satisfaction that intelligible "articulate speech" (Bell's words) could be electrically transmitted. After March 1876, Bell focused on improving the electromagnetic telephone and never used Gray's liquid transmitter in public demonstrations or commercial use. Question: Bell stopped using the liquid-based method after what month?
[EX A]:
March