The correct option is:
In a parliamentary system, the executive is part of the legislature, while in a presidential system, the executive is separate from the legislature.
In a parliamentary system, the executive branch derives its legitimacy from the legislature and is composed of members who are part of the legislative body (e.g., the Prime Minister and the cabinet). The executive can often be dismissed by a vote of no confidence from the legislature.
In contrast, in a presidential system, the executive (the President) is elected independently of the legislature and operates separately from it, which provides a clearer separation of powers. The President does not have the authority to dismiss the legislature, and the legislature cannot easily remove the President without a serious process, such as impeachment.