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.

Read the passage. when mother’s fever persisted for a week, father summoned our family doctor. dr. blakemore applied leeches to mother’s skin in hopes of reducing the amount of blood in her body. despite the doctor’s efforts, she languished in bed for three more days before her appetite returned and she requested a thin broth. our dear cook, mrs. davis, prepared the broth and delivered it to my mother directly, eager to ease her discomfort. what can readers infer about the time period of the passage?