Option A: It is not necessary that all the political parties in the Parliament need to be represented in the Government. The party or the group of parties having a majority of seats form the government. But this statement does not specifically relate to the parliamentary system of government. Hence, option A is incorrect.
Option B: A parliamentary system or parliamentary democracy is a system of democratic governance of a state (or subordinate entity) where the executive derives its democratic legitimacy from its ability to command the confidence of the legislature, typically a parliament, and is also held accountable to that parliament. This means that Option B is correct as the government is responsible to the Parliament and can be removed by it.
Option C: It is a feature of Democracy. It is also a feature of Presidential system (and not just the Parliamentary system). Hence, option C is incorrect.
Option D: The government can be removed before the completion of a fixed term, for instance, by failing a No Confidence Vote. Hence, option D is incorrect.