Urban and rural antonyms or synonyms or neither

Urban means city or surrounded by many.  Rural means country or secluded (set off by itself).  Therefore, these two are antonyms.  A synonym for Urban would be city, crowded, large population.  A synonym for Rural would be country, seclusion, less populated.  Since antonyms are the opposite, that makes urban and rural antonyms.

right angles are formed by perpendicular lines. if the lines would extend, to make two intersecting lines, they would form four right angles.

the answer to "what does the narrator realize by the end of the story" is b.