Final answer:
William Jennings Bryan used a biblical metaphor to argue in favor of free silver primarily to make his argument relatable to a broad audience and to highlight the moral implications, resonating with his listeners' religious and ethical values.
Step-by-step explanation:
William Jennings Bryan employed a biblical metaphor in his advocacy for free silver, a stance he was known for during the late nineteenth century. When you asked why he chose this method, the most suitable options seem to be to emphasize the moral and ethical implications of his stance on free silver (C), as well as to appeal to a wider audience and make his argument more persuasive and relatable (B). In his passionate 'Cross of Gold' speech, he conveyed the message that adopting a silver standard would relieve the economic hardships of working Americans, connecting with populous and moral sentiments.
Bryan's use of biblical imagery aimed to resonate with his audience's values and beliefs, reinforcing his message's ethical dimension and creating a compelling narrative against the gold standard, supported by William McKinley and Republicans. The choice of this metaphor also underscored the perceived injustice of the existing monetary policy, likening it to the crucifixion of Christ, and by extension, the crucifixion of mankind by the gold standard. This speech not only demonstrated his oratory skills but also solidified Bryan's alignment with the interests of farmers and workers against the pro-business, gold-standard platform of the Republicans.