Answer:
C) the relationship between the executive and legislative branches.
Step-by-step explanation:
A parliamentary system is one in which the executive power derives its democratic legitimacy from the trust it receives from the legislative branch. Moreover, the legislative branch is the one that holds the executive accountable. As this is a feature of all parliamentary systems, we can know for sure what the relationship between the executive and the legislative branches is. We cannot know for sure who is allowed to participate in the governing process or what the geographic distribution of power is. Finally, we also do not know whether its laws are collected in a written constitution (for example, the United Kingdom has a parliamentary system and an unwritten constitution).