Rostock represents a major german achievement because germans
a. launched the world's first rocket there
b. dug a new harbor to create a major port
c. connected two major rivers with a canal
d. constructed the world's largest steel mill

Rostock represents a major German achievement because Germans dug a new harbor to create a major port. The correct option among all the options that are given in the question is option "b". During the 19th century, Rostock was the place from where the first propeller driven steamers was constructed.