Final answer:
In the 1896 presidential election, the Democratic Party and the Populist Party both supported William Jennings Bryan as their presidential nominee. Option a is the answer.
Step-by-step explanation:
In the 1896 presidential election, William Jennings Bryan was supported by both the Democratic Party and the Populist Party. The Populist Party faced a critical decision at their convention, ultimately choosing to endorse Bryan but nominating their own vice-presidential candidate, Senator Tom Watson, in an effort to maintain their identity. Despite the endorsement, Bryan was not originally a Populist but rather a Democrat whose views, particularly on silver, resonated with the Populists. This alignment led to Bryan becoming the nominee for both parties, although his campaigns ultimately resulted in defeat against his Republican opposition.