Hi the answer is
D. Trading with other empires
I believe the answer is: D.<span>The people elect representatives, who govern according to the people’s wishes.
Under popular sovereignity, the citizens do not have the power to directly vote for the type of legislation that they desired (in contrast to direct democracy).
But, the citizens could appoint the representative who had similar view and principle with them and give their trust to that representative to make the legislation that would benefit them.</span>