Which sentence uses a prepositional phrase?

a. given the economic and political unrest, the family decided to emigrate.
b. ruling brutally, the harsh dictator caused many people to flee the country.
c. increasing tensions required that international diplomats begin to negotiate.
d. some editorials exposing government corruption were leaked to the public.

The major difference between the communist party in china and political parties in the united states is that a. in the united states, political parties have no role in government. b. in china, the communist party shares power with the national people's congress. c. in the united states, political parties hold widely differing views on almost every topic. d. in china, the communist party runs the government with no opposition.