In a Parliamentary government, the correct unique characteristic is that:
b. the executive office and parliament are the same.
This means that in a Parliamentary system, the executive branch of government, which includes the Prime Minister and the Cabinet, is drawn from the parliament. Unlike in some other systems where the executive and legislative branches are separate, in a Parliamentary system, the executive power is vested in the parliament. This setup allows for a closer relationship between the legislative and executive branches, as the Prime Minister is both the head of government and a member of the parliament.
This unique characteristic gives the Parliament a key role in the functioning of the government, as it is where the executive leadership is formed and held accountable. This arrangement can impact the dynamics of governance and decision-making within the country.