The Highway Act of 1956 was Eisenhower's most significant legislative achievement. The correct option in regards to the given question is option "B". It was not at all a smooth sailing for Eisenhower in respect to passing this important Act. There were wrangling from several directions before it finally got passed in the year of June 1956.This was the law or act that permitted the construction of a national highway spanning 41000 miles with several networks of interstates. Eisenhower felt that this would help in removing traffic jams and also unsafe road conditions.