The correct answer is C) party platforms.
Political party ideologies are based upon party platforms.
Party platforms are the set of principles, goals, strategies, programs, and tactics that form the ideology of a political party. The platform offers a good view of the principles and the foundation of the party and its candidates. Through the platform, citizens learn the perspective of the party on issues such as the economy, politics, security, foreign policy, environment protection, and many more, and the way the party and their candidates plan to address these issues. So yes, political party ideologies are based upon party platforms.