Which statement best describes a difference between presidential and parliamentary democracies?

AIn a parliamentary democracy, the executive and legislative branches are joined. In a presidential democracy, the two branches are separate.
BIn a presidential democracy, the head of government is a member of the legislature. In a parliamentary government, citizens directly elect the head of government.
CIn a presidential democracy, citizens are able to vote for their legislators. In a parliamentary democracy, citizens are not able to vote for their legislators.
DIn a parliamentary democracy, citizens vote directly for the head of government. In a presidential democracy, citizens do not vote directly for the head of government.

The statement that best describes that difference between presidential and parliamentary democracies is that "In a parliamentary democracy, the executive and legislative branches are joined while in a presidential democracy, the two branches are separate".

Both the presidential and parliamentary democracies are branches of democracies although,they are slightly different because of their structural organization.

Hence, the Option A is correct.