The best option that compares the presidential and parliamentary systems of government is:
B) A parliamentary system is volatile and laws are easily reversed, whereas a presidential system is stable and has separation of powers.
This option appropriately highlights the differences in stability and the structure of governance between the two systems. In parliamentary systems, the executive is more directly accountable to the legislature, which can lead to changes in leadership and potentially more frequent shifts in policy. In contrast, presidential systems tend to have more stability due to the separation of powers and the independence of the executive from the legislature.