<em>D. Through the passage of the National Traffic and Motor Vehicle Safety Act</em>
Explanation:
The Great Society were programs started by Lyndon B. Johnson in 1964 and ending in 1965. The goal of the Great Society was to end prejudice among race, poverty among the American people, along with safety and the best outcomes for American citizens.
The National Traffic and Motor Vehicle Safety Act was officially brought together in 1966 and gave the federal government the correct powers to enforce laws having to do with motor vehicles. This mostly had to do with how the vehicles were made or put together and enforced the making of motor vehicles in a safe and correct manor.
One important advantage that primary soruces have over secondary sources is that primary sources offer a firsthand account of an event - b, which isn't the case with secondary sources. Although this leaves primary sources prone to being biased compared to secondary sources.
