The correct answer is A. Designing a platform
Step-by-step explanation:
In politics, the "platform" refers to the goals, projects, ideas, beliefs and ideologies supported by a candidate. This means if political parties design a platform they decide on the goals and projects the candidate but also the position and beliefs of the candidate that are expected would help him/her to get votes and support from citizens. Additionally, in the process of designing a platform political parties focus on addressing complex issues the citizens are interested in. According to this, it is designing a platform the function of political parties that involves putting where a candidate stands on the "issues" into writing.