I think it’s B
Because I did this question
This is a compound sentence, because there are two independent clauses here: 1. Stone bridges are strong + but 2. (strong bridges) are costly to build.
The conjunction 'but' connects two independent clauses, and a compound sentence contains at least two independent clauses, whereas a simple sentence has only one.
Obama was the former president of the United States Of America (USA)
The theme of the poem "Landscape with the Fall of Icarus" by William Carlos Williams is exactly that, the Fall of Icarus. This theme was explored many times throughout many major works, however here it is explored as a background image, not noticed by hardworking people in the sun. Icarus falls and drowns, and nobody bats an eye.