Dubois concludes that the cause of economic progress is possession of political power, civil rights and higher education. This can be seen from the second to the last sentence of the passage, where it is written 'Is it possible and probable that nine millions of men can make effective progress in economic lines, if they are deprived of political rights, made a servile caste and allowed only the most meager chance for developing their exceptional men'.
The war provided Great Britain enormous territorial gains in North America, but disputes over subsequent frontier policy and paying the war's expenses led to colonial discontent, and ultimately to the American Revolution.
C is most likely going to be your answer.
