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: Reflections generally affect polarization. For radio waves, one important reflector is the ionosphere which can change the wave's polarization. Thus for signals received following reflection by the ionosphere (a skywave), a consistent polarization cannot be expected. For line-of-sight communications or ground wave propagation, horizontally or vertically polarized transmissions generally remain in about the same polarization state at the receiving location. Matching the receiving antenna's polarization to that of the transmitter can make a very substantial difference in received signal strength. Question: What reflector can change the waves polarization?
[EX A]: ionosphere

[EX Q]: Passage: After the American Revolutionary War, the number and proportion of free people of color increased markedly in the North and the South as slaves were freed. Most northern states abolished slavery, sometimes, like New York, in programs of gradual emancipation that took more than two decades to be completed. The last slaves in New York were not freed until 1827. In connection with the Second Great Awakening, Quaker and Methodist preachers in the South urged slaveholders to free their slaves. Revolutionary ideals led many men to free their slaves, some by deed and others by will, so that from 1782 to 1810, the percentage of free people of color rose from less than one percent to nearly 10 percent of blacks in the South. Question: Who in the south were urging their churches to free their slaves in the south?
[EX A]: Quaker and Methodist preachers

[EX Q]: Passage: On 2 March 1882, Roderick Maclean, a disgruntled poet apparently offended by Victoria's refusal to accept one of his poems, shot at the Queen as her carriage left Windsor railway station. Two schoolboys from Eton College struck him with their umbrellas, until he was hustled away by a policeman. Victoria was outraged when he was found not guilty by reason of insanity, but was so pleased by the many expressions of loyalty after the attack that she said it was "worth being shot at—to see how much one is loved". Question: What provoked the attack on Queen Victoria as she left Windsor? 
[EX A]:
offended by Victoria's refusal to accept one of his poems