Final answer:
The correct answer is option a) From a monarchy to a constitutional republic.
Step-by-step explanation:
The government shift in Germany from during WWI to after was from a monarchy to a constitutional republic.
After the end of World War I, Germany went through a period of social and political upheaval. The country's political parties forced the kaiser to abdicate, and a new constitutional government, known as the Weimar Republic, was established.
Under the Weimar Republic, Germany became a constitutional monarchy with an elected president and parliament. However, the government was deeply unpopular among many groups, including right-wing nationalists like Adolf Hitler.