I would think B, But i'm not 100% on that, hope this helped!
The sentence is a fragment
A parliamentary system is a system of democratic governance of a state in which the executive branch derives its democratic legitimacy from, and is held accountable to, the legislature (parliament); the executive and legislative branches are thus interconnected. In a parliamentary system, the head of state is normally a different person from the head of government. This is in contrast to a presidential system
in a democracy, where the head of state often is also the head of
government, and most importantly, the executive branch does not derive
its democratic legitimacy from the legislature.
