Answer:
a) Germany.
Step-by-step explanation:
With the unification of Germany rapid economic development began following the industrialisation and by the beginning of the 20th Century Germany was the largest economy in the continental Europe.
Germany was the leader in the production of chemicals and steel. They had high-skilled, well-educated workforce and a strong work ethic which developed the economy. In that way Germany became the powerhouse of Europe. This quick development lead Germany to enter the world wars as the equal power as United Kingdom or United States.