Which BEST describes how a parliamentary democracy differs from a presidential democracy?

Responses
A The legislative branch in the presidential system is always unicameral.The legislative branch in the presidential system is always unicameral.
B In a parliamentary democracy, the head of the government is a member of the legislature.In a parliamentary democracy, the head of the government is a member of the legislature.
C In a presidential democracy, political power is shared between state and federal governments.In a presidential democracy, political power is shared between state and federal governments.
D In a parliamentary democracy there are usually two main political parties; in the presidential system there is only one.

B In a parliamentary democracy, the head of the government is a member of the legislature.