[Q]: Sentence: He concludes that "a well-marked variety may be justly called an incipient species" and that "species are only strongly marked and permanent varieties". Question: What does Darwin theorize about different species with regard to variety?
++++++++++
[A]: yes

[Q]: Sentence: Due to geographical proximity of the Central American countries to the U.S. which has powerful military, economic, and political influences, there were several movements and proposals by the United States during the 19th and 20th centuries to annex some or all of the Central American republics (Costa Rica, El Salvador, Guatemala, Honduras with the formerly British-ruled Bay Islands, Nicaragua, Panama which had the U.S.-ruled Canal Zone territory from 1903 to 1979, and formerly British Honduras or Belize since 1981). Question: When did Panama have the US-ruled Canal Zone Territory?
++++++++++
[A]: yes

[Q]: Sentence: London's ancient core, the City of London, largely retains its 1.12-square-mile (2.9 km2) medieval boundaries and in 2011 had a resident population of 7,375, making it the smallest city in England. Question: On what river is London situated?
++++++++++
[A]:
no