Final Answer:
The development of political parties that worked to promote a specific agenda is most apparent in the early 1800s. Option a is correct.
Step-by-step explanation:
The development of political parties that worked to promote a specific agenda is most apparent in the early 1800s.
The emergence of the second party system composed of the Democrats and the Whigs helped the American people to make sense of the changes affecting the nation. They accepted the idea that permanent political parties would help define the important political and economic issues of the day and provide a means for public debate on those issues.
Therefore, the correct answer is option a. Political parties which worked to promote a specific agenda.