Which sentence uses correct parallel structure?

a. the curricula of most school districts in the united states tends to be dominated by english, math, history, and science is also extremely important as well.
b. the millennial generation faces one of the toughest job markets in american history, large amounts of student debt, and yet it's the most educated.
c. civilization did not emerge in any one place; instead, it developed simultaneously in mesopotamia, the nile river of egypt, and the indus valley.
d. some of the most important figures in american literature include ernest hemingway, emily dickinson, mark twain, and they're all taught in schools.